Subject to errors and alterations! Created by the Aarhus Astronomy Data Centre.

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2 Subject to errors and alterations! Created by the Aarhus Astronomy Data Centre.

3 Contents Contents 1 1 Foreword 7 2 Organization and Practical Information 9 3 Programme 11 4 Social Events 19 I Talks 23 5 Talks: Monday, 9th July 25 G. R. Ricker: Status of the Transiting Exoplanet Survey Satellite (TESS) Mission (Invited) G. Barentsen: Kepler/K2: mission update, legacy dataset overview, and new software tools K. Zwintz: Observing the brightest stars in the sky with BRITE-Constellation and TESS Isabel Colman: Pixel-level analysis of binaries and image subtraction photometry with Kepler & TESS data A. Serenelli: Solar-like oscillations. What have we learned, or not, about stellar physics? (Invited) G. Buldgen: Mean density inversions for red giants and red clump stars S. Khan: The Red-Giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities S. Deheuvels: Searching for red giants passing through the He-flash using seismology 33 J. W. Den Hartogh: Constraining the missing process of angular momentum transport for core Helium burning stars C. Pinçon: Relation between the coupling factor of mixed modes and the internal structure of evolved stars M. Vrard: Structural discontinuities in the core of red giant stars: effect on the mixed-mode pattern and how to measure it N. Giammichele: Seismic cartography of white dwarfs stars from Kepler to TESS: what we can learn from it (Invited) Emily Leiner: Insights in Binary Stellar Evolution from Kepler/K2 (Invited) Zhao Guo: The Synergy Between Binary Stars and Asteroseismoloy: Tides and Mass Transfer C. Johnston: Binary Asteroseismology - Simultaneous and Independent Constraints ( and Headaches ) J. J. Hermes: Rogue waves from parametric resonance in pulsating white dwarfs Talks: Tuesday, 10th July 43 S. E. Thompson: One Telescope, Two Missions, Thousands of Exoplanets (Invited) 44 C. Garraffo: Stellar Activity and its Impact on Exoplanets (Invited) T. S. Metcalfe: A new spin on age-rotation-activity relations with Kepler and TESS 46 R. Kiefer: Modelling Doris frequency shifts The impact of large-scale magnetic fields on stellar oscillation frequencies M. B. Nielsen: Toward Stellar Butterfly Diagrams Benjamin T. Montet: Prospects for exoplanet research with TESS (Invited)

4 Contents H. Kjeldsen: Detection of p-modes in low-snr data: Implications for exoplanet and stellar research S. Grunblatt: Eccentricities and occurrence of planets around oscillating red giants with K M. N. Lund: TESS Data Preparation (Invited) L. Bugnet: FliPer: A new method to rapidly estimate surface gravities with high precision from main sequence to late red giants (0.1 < logg < 4.6 dex) L. F. Pereira: Using Gaussian Processes to model granulation and oscillations in red-giant stars Rich Townsend: GYRE: A Stellar Oscillation Toolkit for the TESS Era Talks: Wednesday, 11th July 57 T. R. White: Interferometry and asteroseismology (Invited) L. Bigot: Realistic modeling of stellar surfaces for better asteroseismic frequencies. (Invited) M. S. Lundkvist: Precise radii from the signature of granulation J. R. Mosumgaard: Using 3D hydrodynamics simulations on-the-fly for stellar evolution calculations O. Benomar: Dependence to surface gravity and temperature of p modes asymmetry in Sun-like stars observed by Kepler M Martig: Galactic archaelogy with Kepler, APOGEE and Gaia (Invited) Marc H. Pinsonneault: APOKASC-2: How well can we measure masses from asteroseismology? B. M. Rendle: Characterising the Vertical Structure of the Milky Way with K Jennifer Johnson: Young alpha-rich stars: the view from K M. Hon: Developing AI Experts in Asteroseismology with Deep Learning Talks: Thursday, 12th July 69 M Ness: Prospects for Galactic Archeology with time-domain data (Invited) A. G. A. Brown: Gaia: mission status and the second data release (Invited) Jamie Tayar: Mixing in Red Giants: The [C/N] Ratio M. Valentini: Ages and masses of metal poor stars O. J. Hall: Testing asteroseismology with Gaia DR2: Position and membership of Red Clump stars W. J. Chaplin: What exoplanet studies need from asteroseismology (Invited) Daniel Huber: The Gaia Revolution of Kepler Stars: Implications for Asteroseismology and Exoplanets V. Van Eylen: An asteroseismic view of the radius gap A. Chontos: Exoplanets Orbiting Asteroseismic Hosts: The Curious Case of KOI-4 78 Cyril Georgy: Convection in massive stars: what can be learnt from hydrodynamics simulations and asteroseismology? (Invited) V. Antoci: Evidence of global Rossby modes in many Kepler intermediate-mass main-sequence stars S. Christophe: Model-independent measurements of gamma Dors internal rotation as a test of angular momentum transport models A. García Hernández: Rotational splitting in δ Scuti stars: the hidden link Talks: Friday, 13th July 83 C. Aerts: Highlights in the variability of OB stars from Kepler/K2 and prospects for TESS (Invited) D. M. Bowman: Unravelling the mysteries of rotation and pulsation in main sequence A and F stars with the Kepler/K2 and TESS space missions. (Invited) 85 M. G. Pedersen: Constraining internal mixing of massive stars from gravity-mode oscillations, surface abundances, and Gaia astrometry

5 Contents G. M. Mirouh: Mode classification in fast-rotating stars using a machine learning algorithm G. Li: Characterisation of gravity and Rossby modes in hundreds of Kepler γ Doradus stars S. Basu: Asteroseismology of solar-like stars with Kepler and K2 (Invited) Joel J. M. Ong: Explaining Deviations from the Scaling Relationship of the Large Frequency Separation B. Nsamba: Asteroseismic modelling of solar-type stars: internal systematics from input physics and surface correction methods K. Verma: Studying mixing in the outer layers using the signatures of acoustic glitches from Kepler data E. P. Bellinger: Testing stellar physics with asteroseismic inversions for the corestructures of solar-type stars T. R. Bedding: The p-g diagram for oscillating subgiants with Kepler and TESS. 94 C. Gehan: Core rotation braking on the red giant branch: characterizing the influence of the mass on the braking efficiency II Posters Posters: Galactic archaeology 99 P18: Á. L. Juhász: Utilising the K2 observations to validate RR Lyrae variables from large sky surveys Posters: Stellar physics 101 P01: D. L. Holdsworth: K2 observations of 33 Lib P02: P. Gaulme: Solar-like oscillators in eclipsing binaries P03: A. Bódi: Asteroseismic analysis and spectrophotometric study of KIC , a Kepler red giant binary with active mass transfer P05: A. R. G. Santos: Determination of surface rotation of Kepler solar-type stars 105 P06: W. Szewczuk: Interpretation of the Kepler data of the rapidly rotating B-type pulsators KIC P07: A. García Saravia Ortiz de Montellano: Automated asteroseismic peak detections P08: A. Derekas: Spectroscopic confirmation of the binary nature of the hybrid pulsator KIC P09: R. Trampedach: Focusing our asteroseismic vision: The surface effect from convection simulations P10: A. Moya: Empirical relations for the estimation of stellar masses and radii P12: P. C. Stine: Local Projective Noise Reduction Techniques for TESS Data P13: M. Lares Martiz: Direct Deconvolution: a method to minimize the effects of the observational window on power spectra P14: D. Slumstrup: Systematical Differences in Spectroscopic Analysis P15: Yaguang Li: Solar-like oscillations in subgiants: mixed mode parameters P16: B. Mosser: The seismic performance P19: B. Buysschaert: Forward seismic modelling of the pulsating magnetic B-type star HD P20: K. J. Bell: The coefficient of variation method: rapid, robust, precise, and fully automated detections of the ν max of solar-like oscillations P22: J. S. Kuszlewicz: Classifying the evolutionary state of Kepler red giants in the time domain P23: O. Creevey: First inferences on HD using asteroseismic data from the Hertzsprung telescope

6 Contents P25: E. Ziaali: The period-luminosity relation for δ Scuti stars using Gaia DR2 parallaxes P26: R. Smolec: Dynamical effects in type II Cepheids P27: N. Jevtic: A nonlinear look at TESS simulated data P28: E. Plachy: Type II and anomalous Cepheids in the K2 mission P29: M. Takata: Theoretical analysis of the evolution of the asymptotic parameters of the dipolar mixed modes of red giant stars P30: A. Thoul: Proper treatment of convective boundaries in stellar evolution codes and their impact on the oscillation spectra of blue supergiants P31: E. Brunsden: Spectroscopic Pulsational Analysis of Southern γ Doradus Stars 126 P32: J. S. Kuszlewicz: Are Stellar Inclination Angles Distributed Randomly? P33: S. Mathur: Correlation between the non detection of acoustic modes in solarlike stars and their magnetic activity P34: B. Mosser: Period spacings in red giants: toward a complete description of the mixed-mode pattern P35: K. J. Bell: Resolving Space-Photometry Nyquist Ambiguities from the Ground130 P36: E. Hartig: K2: A Search for Very Red Stellar Objects P37: J. M. Benkő: Additional modes and cyce-to-cycle variations in non-blazhko RR Lyrae stars P38: J. Goldstein: Toward robust mapping of instability strips: a new numerical method for finding non-adiabatic eigenfrequencies P39: E. Corsaro: Constraining the photon-axion coupling factor in the Sun through oscillation frequency separation ratios P40: J. Pascual-Granado: Observing stellar flares in A-type stars observed by Kepler data with Bayesian Blocks and Super-resolution techniques P41: J. C. Suárez: On the use of the Shannon s information entropy to estimate stellar densities P43: S. Sekaran: Two s a Crowd: Characterising the effect of photometric contamination on the extraction of global asteroseismic parameters in Red-Giant Binaries P45: M. Skarka: Radial velocity measurements with the Perek telescope P46: L. Manchon: Influence of metallicity on the surface effect P47: R. Collet: Stagger p-drive: studying excitation and damping of p-mode oscillations with 3D simulations P48: A. Stokholm: HR 7322: A benchmark for stellar evolution P49: G. Houdek: Damping rates and frequency corrections of LEGACY stars P50: D. Pricopi: Modelling the rotating red giant star KIC using Kepler data P51: L. S. Viani: Investigating the Metallicity-Mixing Length Relation P52: T. R. Shutt: Characterisation of pulsations in γ Doradus candidate stars using high resolution spectroscopy and photometry P54: D. Buzasi: Choosing Wisely: The Effects of Algorithms and Observing Windows on Rotation-Activity Studies P56: A. E. L. Thomas: Constraining the Magnetic Activity Distribution on Other Stars using Asteroseismology P57: J. Yu: Predicting radial-velocity jitter induced by stellar oscillations based on Kepler data P58: P. Houdayer: A simple tool for calculating centrifugal deformation starting from 1D stellar models P59: Tanda Li: Asteroseismic modelling of sub giants: key to accurate stellar ages 150 P60: J. K. S. S. (1), K. K. (1), E. U. (1), P. S. (1): The difference is in the detail: light curve shapes of RRab stars from Kepler/K2 data P61: A. R. G. Santos: On the limits of seismic inversions for radial differential rotation of solar-type stars

7 Contents P62: Jean McKeever: Further constraints on the age and helium abundance of NGC 6791 from modeling of the asteroseismic oscillations P63: B. Evano: Chaotic pressure modes in rapidly rotating stars P64: D. Stello: Is the single-referee review process broken? P66: R-M. Ouazzani: γ Doradus stars as test of angular momentum transport models156 P67: P. G. Beck: Seismic Probing of the first dredge-up event and tidal interactions in red-giant binaries P68: Z. Vanderbosch: Asteroseismology of DBVs with K2 -precision light curves P69: I. W. Roxburgh: Overfitting and correlations in model fitting with frequency ratios P70: Tao Wu: Dipolar modes and the size of helium core on red giants Posters: Space missions 161 P04: László Molnár: Extending asteroseismology to extragalactic Cepheids with K2 162 P11: S. Frandsen: TESS/SONG observations P17: K. Trelborg: Delphini-1 - Aarhus University s First Satellite P24: V. A. Marchiori: The PLATO mission: conceiving optimal aperture masks for in-flight photometry P42: S. E. Mullally: Accessing TESS Data at the MAST P44: R. Szabo: The Kepler Pixel Project P53: D. Buzasi: Removing Instrumental Signatures from TESS Data Using an Ensemble Photometry Approach P55: G. Tautvaišienė: Ground-based Observations for the TESS Space Mission P65: A. Moya: The asteroseismic potential of CHEOPS List of Participants 171 5

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9 Foreword The TASC4/KASC11 Workshop First light in a new era of astrophysics 1 Asteroseismology has become a well established field with far reaching implications in many areas of astrophysics thanks to the advent of space-borne missions. The analysis of data acquired by the nominal Kepler mission and its extension the K2 mission has opened a window towards physical processes never seen before in stars, challenged our understanding of stellar evolution across the Hertzsprung-Russell diagram, drastically changed the reigning paradigm on exoplanet demographics and added a new dimension to the study of the Milky Way. Bearing the lessons learned in mind, we are now at the break of a new era for stellar-, exoplanet-, and Galactic studies inaugurated by the first light from the Transiting Exoplanet Survey Satellite (TESS). TASC4/KASC11 will be the first meeting after the launch of the TESS satellite and will particularly focus on its prospects for breakthrough science in the fields of stellar evolution, exoplanet research and Galactic archaeology. It will review the latest highlights from Kepler and K2 and how the challenges presented by these results can be addressed in the dawn of the new era of astrophysical research at a much larger scale. The workshop will also provide sessions for discussion within TASC working groups and coordinated activities on the status of preparations for the imminent data flow from TESS. I look forward to a week that I am sure will be remembered as another turning point in the history of asteroseismology. Welcome to Aarhus. Víctor Silva Aguirre 7

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11 Organization and Practical Information Scientific Organising Committee (SOC) 2 Víctor Silva Aguirre, Denmark (Chair) Suzanne Aigrain, UK Tom Barclay, USA Remo Collet, Denmark Margarida Cunha, Portugal JJ Hermes, USA Jennifer Johnson, USA Yveline Lebreton, France Coralie Neiner, France Dennis Stello, Australia Vincent Van Eylen, The Netherlands Local Organising Committee (LOC) Rasmus Handberg (Chair) Louise Børsen-Koch Brigitte Henderson Ole J. Knudsen Hans Kjeldsen Ditte Slumstrup Questions and help The conference secretary, Brigitte Henderson, will be available at the registration desk by the entrance to the math department building each day from 08:30 12:00, and will be available on or phone. brigitte@phys.au.dk Phone: Name badge The name badge and tickets issued to you on registration are your admission to all scientific sessions, lunches, coffee breaks and for the social events. You are therefore kindly requested to wear your name badge on all occasions. If the badge is lost, please contact Brigitte Henderson (brigitte@phys.au.dk). Wireless Internet Wireless networks are available throughout the Aarhus University campus, including the conference venue and meeting rooms. If you have the possibility to use the eduroam wireless network, we will encourage you to do so, as this provides the maximal security for you and the minimal effort. This requires that you have already set it up with your home-institution. Otherwise you can use the AU-Guest wireless network, where you can log in using e.g. a Google or Facebook account. Just open a browser and you should be directed to a page explaining how to log in. 9

12 Organization and Practical Information Mobile phones We kindly request all participants to keep mobile phones on mute in the auditorium during the scientific sessions. Speakers All speakers must ensure that their talk is uploaded to the computer provided in the auditorium, in good time before the start of the session. A member of the local organising committee will be present in the auditorium before the start of a session to assist you. Session chairs We kindly ask the session chairs to be present in the auditorium at least 10 minutes before the beginning of the session. Lunch A buffet lunch will be provided for all participants of the conference. Lunch will be held in the math canteen which is in the same building as the conference venue. Your conference name badge will be required for entry to the lunches. Only exception will be Wednesday where we will get a packed lunch before the excursion. Social Media Conference hashtag: #TASC4 Stellar Astrophysics Centre on social media: Facebook: facebook.com/sacscience 10

13 Programme Sunday, 8th July :00 20:00 Welcome Reception and registration Physics Canteen, Department of Physics and Astronomy Monday, 9th July :30 08:50 Registration 08:50 09:00 Welcome Session I: Space missions. Chair: Víctor Silva Aguirre. 09:00 09:30 G. R. Ricker (Invited) Status of the Transiting Exoplanet Survey Satellite (TESS) Mission 09:30 09:50 G. Barentsen Kepler/K2: mission update, legacy dataset overview, and new software tools 09:50 10:10 K. Zwintz Observing the brightest stars in the sky with BRITE-Constellation and TESS 10:10 10:30 I. Colman Pixel-level analysis of binaries and image subtraction photometry with Kepler & TESS data 10:30 11:00 Coffee Session II: Stellar Physics. Chair: Dennis Stello. 11:00 11:30 A. Serenelli (Invited) Solar-like oscillations. What have we learned, or not, about stellar physics? 11:30 11:50 G. Buldgen Mean density inversions for red giants and red clump stars 11:50 12:10 S. Khan The Red-Giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities 12:10 12:30 S. Deheuvels Searching for red giants passing through the He-flash using seismology 12:30 14:00 Lunch Session II: Stellar Physics (continued). Chair: Dennis Stello. 14:00 14:20 J. W. Den Hartogh Constraining the missing process of angular momentum transport for core Helium burning stars 14:20 14:40 C. Pinçon Relation between the coupling factor of mixed modes and the internal structure of evolved stars 11

14 Programme 14:40 15:00 M. Vrard Structural discontinuities in the core of red giant stars: effect on the mixedmode pattern and how to measure it Session II: Exotic stellar evolution. Chair: Jørgen Christensen-Dalsgaard. 15:00 15:30 N. Giammichele (Invited) Seismic cartography of white dwarfs stars from Kepler to TESS: what we can learn from it 15:30 16:00 E. Leiner (Invited) Insights in Binary Stellar Evolution from Kepler/K2 16:30 16:30 Coffee Session II: Exotic stellar evolution (continued). Chair: Jørgen Christensen-Dalsgaard. 16:30 16:50 Zhao Guo The Synergy Between Binary Stars and Asteroseismoloy: Transfer Tides and Mass 16:50 17:10 C. Johnston Binary Asteroseismology - Simultaneous and Independent Constraints ( and Headaches ) 17:10 17:30 J. J. Hermes Rogue waves from parametric resonance in pulsating white dwarfs 17:30 18:05 Poster presentations (Posters 1 30) 19:30 Astronomer Mixer 12

15 Programme Tuesday, 10th July 2018 Session III: Activity and exoplanets. Chair: Vincent Van Eylen. 08:30 09:00 S. E. Thompson (Invited) One Telescope, Two Missions, Thousands of Exoplanets 09:00 09:30 C. Garraffo (Invited) Stellar Activity and its Impact on Exoplanets 09:30 09:50 T. S. Metcalfe A new spin on age-rotation-activity relations with Kepler and TESS 09:50 10:10 R. Kiefer Modelling Doris frequency shifts The impact of large-scale magnetic fields on stellar oscillation frequencies 10:10 10:30 M. B. Nielsen Toward Stellar Butterfly Diagrams 10:30 11:00 Coffee Session III: Activity and exoplanets (continued). Chair: Vincent Van Eylen. 11:00 11:30 B. T. Montet (Invited) Prospects for exoplanet research with TESS 11:30 11:50 H. Kjeldsen Detection of p-modes in low-snr data: Implications for exoplanet and stellar research 11:50 12:10 S. Grunblatt Eccentricities and occurrence of planets around oscillating red giants with K2 12:10 12:30 Poster presentations (Posters 31 45) 12:30 14:00 Lunch Lunch Meeting: TASC Steering Committee Session I: Space missions (continued). Chair: JJ Hermes. 14:00 14:30 M. N. Lund (Invited) TESS Data Preparation 14:30 14:50 L. Bugnet FliPer: A new method to rapidly estimate surface gravities with high precision from main sequence to late red giants (0.1 < log g < 4.6 dex) 14:50 15:10 L. F. Pereira Using Gaussian Processes to model granulation and oscillations in red-giant stars 15:10 15:30 R. Townsend GYRE: A Stellar Oscillation Toolkit for the TESS Era 15:30 16:00 Coffee 16:00 16:30 Poster presentations (Posters 46 70) 13

16 Programme Special Session: TASC splinter sessions 16:30 17:30 TASC Splinter Sessions: WG-1 & WG-2 (Solar-like stars and exoplanet hosts) Aud. E WG-4 & WG-5 (Main Sequence classical pulsators) Aud. D1 WG-6 (RR Lyrae stars and Cepheids) Aud. D2 17:30 19:30 Posters and beer 14

17 Programme Wednesday, 11th July 2018 Session II: Stellar physics (continued). Chair: Remo Collet. 08:30 09:00 T. R. White (Invited) Interferometry and asteroseismology 09:00 09:30 L. Bigot (Invited) Realistic modeling of stellar surfaces for better asteroseismic frequencies. 09:30 09:50 M. S. Lundkvist Precise radii from the signature of granulation 09:50 10:10 J. R. Mosumgaard Using 3D hydrodynamics simulations on-the-fly for stellar evolution calculations 10:10 10:30 O. Benomar Dependence to surface gravity and temperature of p modes asymmetry in Sunlike stars observed by Kepler 10:30 11:00 Coffee Session IV: Galactic archaeology. Chair: Remo Collet. 11:00 11:30 M. Martig (Invited) Galactic archaelogy with Kepler, APOGEE and Gaia 11:30 11:50 M. H. Pinsonneault APOKASC-2: How well can we measure masses from asteroseismology? 11:50 12:10 B. M. Rendle Characterising the Vertical Structure of the Milky Way with K2 12:10 12:30 J. Johnson Young alpha-rich stars: the view from K2 12:30 12:50 M. Hon Developing AI Experts in Asteroseismology with Deep Learning 12:30 12:50 O. J. Knudsen Introduction to excursion 13:05 13:45 Lunch 13:45 18:00 Excursion: Moesgaard 15

18 Programme Thursday, 12th July Session IV: Galactic archaeology (continued). Chair: Jennifer Johnson. 08:30 09:00 M. Ness (Invited) Prospects for Galactic Archeology with time-domain data 09:00 09:30 A. G. A. Brown (Invited) Gaia: mission status and the second data release 09:30 09:50 J. Tayar Mixing in Red Giants: The [C/N] Ratio 09:50 10:10 M. Valentini Ages and masses of metal poor stars 10:10 10:30 O. J. Hall Testing asteroseismology with Gaia DR2: Position and membership of Red Clump stars 10:30 11:00 Coffee Session V: Asteroseismology and exoplanets. Chair: Tom Barclay. 11:00 11:30 W. J. Chaplin (Invited) What exoplanet studies need from asteroseismology 11:30 11:50 D. Huber The Gaia Revolution of Kepler Stars: Implications for Asteroseismology and Exoplanets 11:50 12:10 V. Van Eylen An asteroseismic view of the radius gap 12:10 12:30 A. Chontos Exoplanets Orbiting Asteroseismic Hosts: The Curious Case of KOI-4 12:30 14:00 Lunch Session II: Stellar physics (continued). Chair: Yveline Lebreton. 14:00 14:30 C. Georgy (Invited) Convection in massive stars: what can be learnt from hydrodynamics simulations and asteroseismology? 14:30 14:50 V. Antoci Evidence of global Rossby modes in many Kepler intermediate-mass mainsequence stars 14:50 15:10 S. Christophe Model-independent measurements of gamma Dors internal rotation as a test of angular momentum transport models 15:10 15:30 A. García Hernández Rotational splitting in δ Scuti stars: the hidden link 15:30 16:00 Coffee 18:00 22:00 Conference Dinner Tivoli Friheden

19 Programme Friday, 13th July 2018 Session II: Stellar physics (continued). Chair: Hans Kjeldsen. 08:30 09:00 C. Aerts (Invited) Highlights in the variability of OB stars from Kepler/K2 and prospects for TESS 09:00 09:30 D. M. Bowman (Invited) Unravelling the mysteries of rotation and pulsation in main sequence A and F stars with the Kepler/K2 and TESS space missions. 09:30 09:50 M. G. Pedersen Constraining internal mixing of massive stars from gravity-mode oscillations, surface abundances, and Gaia astrometry 09:50 10:10 G. M. Mirouh Mode classification in fast-rotating stars using a machine learning algorithm 10:10 10:30 G. Li Characterisation of gravity and Rossby modes in hundreds of Kepler γ Doradus stars 10:30 11:00 Coffee Session II: Stellar physics (continued). Chair: Víctor Silva Aguirre. 11:00 11:30 S. Basu (Invited) Asteroseismology of solar-like stars with Kepler and K2 11:30 11:50 J. J. M. Ong Explaining Deviations from the Scaling Relationship of the Large Frequency Separation 11:50 12:10 B. Nsamba Asteroseismic modelling of solar-type stars: internal systematics from input physics and surface correction methods 12:10 12:30 K. Verma Studying mixing in the outer layers using the signatures of acoustic glitches from Kepler data 12:30 14:00 Lunch Session II: Stellar physics (continued). Chair: Víctor Silva Aguirre. 14:00 14:20 E. P. Bellinger Testing stellar physics with asteroseismic inversions for the core-structures of solar-type stars 14:20 14:40 T. R. Bedding The p-g diagram for oscillating subgiants with Kepler and TESS 14:40 15:00 C. Gehan Core rotation braking on the red giant branch: characterizing the influence of the mass on the braking efficiency 17

20 Programme Closing 15:00 15:20 J. Christensen-Dalsgaard Closing remarks 15:20 15:30 Poster and contributed talk prizes 15:30 16:00 Coffee 18

21 4 Social Events Welcome Reception, Sunday 8th July All participants and accompanying persons are invited to a welcome reception at the Physics Canteen at the Department of Physics and Astronomy, Sunday 8th July at 17:00 20:00. This is also where you register for the workshop. The address is Ny Munkegade 120, 8000 Aarhus C. Please enter the building via the main entrance to the department as indicated on the map below. The reception will be on the 7th floor and signs will guide you the right way. Astronomers Mixer, Monday 9th July This year s (Young) Astronomers Mixer will be Monday 9th July at Tìr na nóg, located in the centre of Aarhus. As usual, age itself is an irrelevant parameter to determine whether you are young or not, so everyone is welcome from 19:30 22:00! Read more about the venue here: Posters and beer, Tuesday 10th July The poster session will be Tuesday. This year we will combine poster viewing with beer on tap from our local brewery Aarhus Bryghus. 19

22 Social Events Workshop Excursion, Wednesday 11th July The TASC4/KASC11 Workshop excursion will bring the past to fascinating life at the Moesgaard Museum in Aarhus, which has two Michelin stars in the Michelin attraction s guide. Prehistory presented innovatively in a breathtaking architectural setting makes for a world-class museum experience when you visit the Moesgaard Museum. The past becomes alive and the people in the exhibits will step forward and provide the visitors with a better understanding of the past and how we arrived at where we are in the present. Programme 13:45 Departure directly for the Moesgaard Museum from the large parking area North of building 1520 with busses. Important: Bring your nametags! 14:30 Arrival at Moesgaard Museum. Locker room, distribution of tickets, find your group. 14:45 Guided tours in groups of 20, in English. 15:50 Free time in the rest of the museum, or take a stroll in the park by the Manor House downhill. 17:00 Sharp! All have to present in the entrance area by the lawn. Viking age snacks and a taste of mead will be served while you mingle. 18:00 Departure by bus. Or, if you like, and weather permits take a 2 km stroll through the forest to the beach where the yellow city bus can take you back downtown (bring Danish money). For the very tough you can also walk along the beach the 10 km back to the city, and maybe take a dip on the way. Please remember to wear practical footwear for the excursion. All participants who indicated when registering online for the conference that they would like to participate in the excursion, will have to bring the conference name badge to attend. Conference Dinner, Thursday 12th July The conference dinner will be at Restaurant Terrassen, located beautifully at Tivoli Friheden in the forest close to Aarhus City. You will both be able to enjoy the rides in the Tivoli, some good food and each others company. There is no additional cost for this event; the conference dinner is included in the registration fee. All participants who indicated when registering online for the conference that they would like to attend the conference dinner, will have to bring their name badge to enter the park. Programme 17:30 Departure from the University by bus. 17:40 Pick-up of participants downtown (the location will be specified). 18:00 Arrival at Tivoli Friheden. 18:00 18:30 Welcome address and drinks. 18:30 19:30 Free time in Tivoli. You will be provided with a tour-pass and free drinks! 20

23 Social Events 19:30 22:00 Conference Dinner. 22:15 Departure by bus. Find more information about Tivoli Friheden here: Address: Skovbrynet 5, 8000 Aarhus C 21

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27 Talks: Monday, 9th July 5 25

28 Talks: Monday, 9th July Status of the Transiting Exoplanet Survey Satellite (TESS) Mission (Invited) G. R. Ricker 1 (1) MIT Kavli Institute for Astrophysics and Space Research. The Transiting Exoplanet Survey Satellite (TESS) will discover thousands of exoplanets in orbit around the brightest stars in the sky. In a two-year survey, TESS will monitor 200,000 pre-selected bright stars for planetary transits in the solar neighborhood at a 2- minute cadence. The survey will identify planets ranging from Earth-sized to gas giants, around a wide range of stellar types and orbital distances. TESS will also provide full frame images (FFI) at a cadence of 30 minutes or less. These FFI will provide precise photometric information for every object within the 2300 square degree instantaneous field of view of the TESS cameras. In total, more than 30 million stars and galaxies brighter than magnitude I=16 will be precisely photometered during the two-year prime mission. The lunar-resonant TESS orbit will provide opportunities for an extended mission lasting more than a decade, with data rates of 100 Mbits/s. An extended survey by TESS of regions surrounding the North and South Ecliptic Poles will provide prime exoplanet targets for characterization with the James Webb Space Telescope, as well as other large ground-based and space-based telescopes of the future. The TESS legacy will be a catalog of the nearest and brightest main-sequence stars hosting transiting exoplanets, which should endure as the most favorable targets for detailed future investigations. As part of TESS s asteroseismology effort, the target list provides for short cadence observations of the 10,000 brightest stars in the sky. TESS was launched as a NASA Astrophysics Explorer from Cape Canaveral by a SpaceX Falcon 9 on 18 April The satellite achieved its final science orbit on 30 May First light results from the TESS mission will be presented. 26

29 Talks: Monday, 9th July Kepler/K2: mission update, legacy dataset overview, and new software tools G. Barentsen 1 J. Dotson 1, C. Hedges 1 (1) Kepler/K2 Mission, NASA Ames Research Center, USA. The K2 survey has expanded the Kepler legacy by using the repurposed spacecraft to observe a selection of fields along the ecliptic plane. The K2 dataset now includes nearly 2,000 targets observed at 1-minute cadence and over 300,000 targets at 30-minute cadence, including many bright and pulsating stars amenable to asteroseismology. Notably, K2 recently observed open and globular clusters at all ages, including very young (1-10 Myr, e.g. Taurus, Upper Sco, NGC 6530), moderately young (0.1-1 Gyr, e.g. M35, M44, Pleiades, Hyades), middle-aged (e.g. M67, Ruprecht 147, NGC 2158), and old globular clusters (e.g. M9, M19, Terzan 5). K2 observations of stellar clusters are exploring the rotation period-mass relationship to significantly lower masses than was previously possible, shedding light on the angular momentum budget and its dependence on mass, age, and multiplicity. I will review the targets and star clusters sampled by K2 across 18 fields so far, highlighting several unexplored uses of the public data set along the way. With fuel running out in 2018, I will discuss the data archive and TESS-compatible software tools the K2 mission intends to leave behind for posterity. In particular, I will highlight Kepler s new Python data analysis package, called lightkurve, which is accompanied by a rich set of tutorials to help new scientists enter the field across the next decade (URL: 27

30 Talks: Monday, 9th July Observing the brightest stars in the sky with BRITE-Constellation and TESS K. Zwintz 1 (1) University of Innsbruck, Institute for Astro- and Particle Physics. During their more than five years in space, the five BRITE-Constellation nano-satellites have completed observations of more than 550 individual targets brighter than about 6th magnitude. The data have allowed us to study a variety of variability phenomena covering a wide range across the HR-diagram including different types of pulsations, wind phenomena, rapidly rotating stars (e.g. Be), binary and multiple systems, and stars with planets. Some of the prime science results therefore comprise the discovery of massive heartbeat systems, the apparent interaction of phenomena on very different time scales in Be stars, the proof of a photospheric connection for the wind variations in very massive stars, g-modes and g-mode period spacings in β Cephei, SPB and γ Doradus stars or the presence of only two pulsation modes in a magnetic δ Scuti star. I will give an overview of the latest scientific results obtained from BRITE-Constellation data and discuss the potential synergies between TESS and BRITE-Constellation. 28

31 Talks: Monday, 9th July Pixel-level analysis of binaries and image subtraction photometry with Kepler & TESS data Isabel Colman 1,2 Tim Bedding 1,2, Daniel Huber 1,3, Hans Kjeldsen 2 (1) Sydney Institute for Astronomy, School of Physics, University of Sydney, Australia. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. (3) Institute for Astronomy, University of Hawai i, USA. We present novel data analysis techniques applied to Kepler pixel data of multiple stellar systems and associated phenomena, with a view to apply these techniques to TESS data. Close examination of pixel data is a trusted method to locate the source of a signal; for multiple stellar systems with asteroseismically distinct signals, we can examine each individual pixel around a target in Fourier space. We demonstrate this method on a sample of red giants with anomalous high amplitude peaks in their Fourier spectra, and on a potential red giant-delta Scuti binary. With many such objects to be discovered, we plan to continue to use this method to examine asteroseismically interesting targets among TESS data. Additionally, we present a method of utilising Kepler pixel data in an image subtraction routine to extract time series which emphasise variability. Such methods are of most use in crowded fields and on data with relatively wide pixels, such as we will soon have from TESS. We present a proof-of-concept using Kepler data and simulated TESS data. 29

32 Talks: Monday, 9th July Solar-like oscillations. What have we learned, or not, about stellar physics? (Invited) (1) Institute of Space Sciences (ICE, CSIC). (2) Institut d Estudis Espacials de Catalunya. A. Serenelli 1,2 In this talk I will present an overview of the impact asteroseismology has had in our understanding of the structure and physical processes in low-mass stars displaying solar-like oscillations. Some of the physical processes to be discussed are: near-surface convection, core overshooting, microscopic diffusion, mass loss, and stellar rotation. 30

33 Talks: Monday, 9th July Mean density inversions for red giants and red clump stars G. Buldgen 1 A. Miglio 1, B. Rendle 1, D. R. Reese 2, G. R. Davies 1 (1) HiROS, University of Birmingham, United Kingdom. (2) LESIA, Observatoire de Paris-Meudon, France. Since the CoRoT (Baglin et al. 2009) and Kepler missions (Borucki et al. 2010), the availability of thousands of high quality seismic spectra for red giants led to their use as the standard clocks and rulers (Miglio et al. 2015A, Silva Aguirre et al. 2018) for Galactic Archeology (Miglio et al. 2015A, Anders et al. 2017). New data is also expected from the TESS and PLATO (Rauer et al. 2014) missions, which will play a key role in Galactic studies Miglio et al. (2017). These successes stem from the ability of asteroseismology to provide precise masses and radii for a large number of stars. The seismic determination of these quantities are based on so-called scaling laws, which have also been used extensively for main-sequence stars. In this study, we will show how the SOLA inversion technique adapted for mean density determinations from Reese et al. (2012) can be used on the radial oscillations of red giants to provide more robust and accurate determinations of the mean density. In combination with radii determinations from GAIA, this approach will provide more robust, less model-dependent masses to help accurately dissect the structure and history of the Galaxy. We will present results on artifical seismic data of standard models, models including an extended atmosphere from averaged 3D simulations and nonadiabatic frequency calculations to test the surface effects as well as on some targets of the sample of eclipsing binaries from Gaulme et al. (2016) and Brogaard et al. (2018). 31

34 Talks: Monday, 9th July The Red-Giant Branch Bump Revisited: Constraints on Envelope Overshooting in a Wide Range of Masses and Metallicities S. Khan 1,2 O. J. Hall 1,2, A. Miglio 1,2, G. R. Davies 1,2, B. Mosser 3, L. Girardi 4, J. Montalbán 5 (1) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, 8000 Aarhus C, Denmark. (3) LESIA, Observatoire de Paris, PSL Research University, Université Pierre et Marie Curie, Université Denis Diderot, Meudon Cedex, France. (4) INAF - Osservatorio Astronomico di Padova, Vicolo dell Osservatorio 5, I Padova, Italy. (5) Dipartimento di Fisica e Astronomia Galileo Galilei, Università di Padova, Vicolo dell Osservatorio 3, I Padova, Italy. The red-giant branch bump provides valuable information for the investigation of the internal structure of low-mass stars. Because current models are unable to accurately predict the occurrence and efficiency of mixing processes beyond convective boundaries, one can use the luminosity of the bump a diagnostic of the maximum extension of the convective envelope during the first-dredge up as a calibrator for such processes. An improved description of mixing beyond convective envelopes has wide-ranging applications from the properties of the tachocline and the lithium depletion in Sun-like stars, through the evolution of red-giant branch and asymptotic-giant branch stars, to the onset of blue loops in intermediate and massive stars. By combining asteroseismic and spectroscopic constraints, we expand the analysis of the bump to masses and metallicities beyond those previously accessible using globular clusters. Our dataset comprises nearly 3000 red-giant stars observed by Kepler and with APOGEE spectra. Using statistical mixture models, we are able to detect the bump in the average seismic parameters ν max and ν, and show that its observed position reveals general trends with mass and metallicity in line with expectations from models. Moreover, our analysis indicates that standard stellar models underestimate the depth of efficiently mixed envelopes. The inclusion of significant overshooting from the base of the convective envelope, with an efficiency that increases with decreasing metallicity, allows to reproduce the observed location of the bump. Interestingly, this trend was also reported in previous studies of globular clusters. The second Data Release of Gaia will allow a significant step forward in characterising the bump. We will discuss how, with precise and accurate parallaxes available, one can avoid, or mitigate, theoretical and observational uncertainties, e.g. by comparing the bump luminosity with that of the zero-age horizontal branch or the main-sequence turn off. 32

35 Talks: Monday, 9th July Searching for red giants passing through the He-flash using seismology S. Deheuvels 1 (1) IRAP, Université de Toulouse, CNRS, CNES, UPS, (Toulouse), France. For first-ascent red giants with masses below 2 M, the ignition of helium in the degenerate core leads to a thermal runaway, known as the He core flash. While the basic features of the He flash have been known for decades, the details of the progressive removal of electron degeneracy in the core and the timescale over which it occurs remain very uncertain. 1D evolution codes predict the existence of a series of He subflashes, whose cumulative duration could lead us to expect several tens of giants in this stage of evolution among the Kepler data. During subflashes, the He burning shell is convective, which splits the cavity of g modes in two separate cavities. We therefore expect the oscillation spectrum to be modified during these phases. We here investigate whether this could be used to seismically identify red giants passing through the He flash. For this purpose, we use the JWKB approximation to calculate the asymptotic mode frequencies during a subflash, taking into account the three propagating cavities (the p-mode cavity and the two g-mode cavities). We also estimate the expected mode heights, taking into account the effects of radiative damping in the core. Our results are then compared to the oscillation spectra calculated numerically with ADIPLS and GYRE. We eventually find that red giants going through He subflashes could be identified by clear, recognizable features in their oscillation spectra, which are described in this presentation. We also report on the first efforts made to search for such features among the 15,000 red giants observed with the Kepler satellite. 33

36 Talks: Monday, 9th July Constraining the missing process of angular momentum transport for core Helium burning stars J. W. Den Hartogh 1,2 P Eggenberger 3, R Hirschi 2,4 (1) Konkoly Observatory, Budapest, Hungary. (2) Astrophysics group, Keele University, UK. (3) Observatoire de Genève, Université de Genève, Switserland. (4) Kavli Institute for the Physics and Mathematics of the Universe (WPI), University of Tokyo, Japan. It is now well known that there is a discrepancy between the core rotation rates measured by asteroseismic surveys and the rates calculated by stellar evolution codes. This discrepancy indicates the presence of an unknown process of angular momentum transport. We will present a study focussing on core Helium burning stars, for which core and surface rotation rates are determined by Deheuvels(2015). We first compare 2.5 M models that include the Tayler-Spruit dynamo to the data from Deheuvels(2016). We then determine the efficiency of the unknown transport process by computing models with an additional viscosity as in Eggenberger(2012, 2017). Models with a viscosity that depends on the degree of radial differential rotation as in Spada(2016) are finally studied. We find that, like Cantiello(2014) showed for 1.5 M models, the TS-dynamo does not provide enough coupling between core and envelope in our 2.5 M models to match asteroseismic observations of core Helium burning stars. The additional viscosity needed for these stars can be precisely determined from asteroseismic data. We find that the efficiency of the undetermined process is higher for these core Helium burning stars than for less evolved and less massive red giants. This is in good agreement with previous results obtained for red giant stars that show an increase of the efficiency of the unknown transport mechanism both with the evolution and the mass of the star. We also find that models including an additional viscosity that do match the asteroseismic observations, have rotation periods in the white dwarf phase that are too long when compared to white dwarf observations. This suggests that the efficiency of the missing process of angular momentum transport decreases after the core Helium burning phase. Such a decrease cannot be reproduced by a viscosity that only depends on the degree of radial differential rotation. 34

37 Talks: Monday, 9th July Relation between the coupling factor of mixed modes and the internal structure of evolved stars C. Pinçon 1,2 K. Belkacem 2, M.-J. Goupil 2 (1) Institut d Astrophysique Spatiale, UMR8617, CNRS, University Paris XI, France. (2) LESIA, Paris Observatory, PSL Research University, CNRS, University Pierre et Marie Curie, University Paris Diderot, France. The space-borne missions CoRoT and Kepler provided a lot of stringent constraints on the interior of thousands of evolved stars. In particular, the detection of mixed modes gave us insights into the properties of their inner layers. Among the main results is the measurement of the dipolar period-spacing, Π 1, that is correlated to the mass of their helium core. With the large separation ν, they permit, for example, to discriminate between the stars on the red giant branch and those on the red clump. However, all the potential of mixed modes has not been exploited yet. Among the other seismic parameters associated with mixed modes, special cares have recently been given to the coupling factor q, which describes the degree of interaction between the central and the external resonant cavities. This parameter is expected to provide information on the intermediate evanescent zone, located between the hydrogen-burning-shell and the neighborhood of the base of the convective zone in these stars. The large-scale measurement by Mosser et al. (2017) showed that q varies during evolution, with clear signatures at the transition from the subgiant to the red giant phases as well as at the transition to the red clump. This work also demonstrated that the strong coupling hypothesis is required to reproduce the observations. However, the link between the variations in q and the internal structure still needs to be precisely established. During this talk, we investigate the relation between q and the internal properties of the evanescent zone considering the asymptotic analyses of Shibahashi (1979) and Takata (2016) in the weak and the strong coupling hypotheses, respectively. Using a simplified modeling of the evanescent zone, we first derive an analytical expression of the coupling factor that emphasizes the physical quantities of interest on which it depends. The lessons learned from this preliminary study are then used to interpret the observed variations in q in terms of structural changes during evolution by means of stellar models. We finally discuss the results and highlight how the measurement of q can contribute to a better characterization of stars. 35

38 Talks: Monday, 9th July Structural discontinuities in the core of red giant stars: effect on the mixed-mode pattern and how to measure it M. Vrard 1 M. S. Cunha 1, B. Mosser 2 (1) Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, , Porto, Portugal. (2) PSL, LESIA, CNRS, Université Pierre et Marie Curie, Université Denis Diderot, Observatoire de Paris, Meudon cedex, France. The space mission Kepler has provided seismic data of unprecedented quality which brought new ways to precisely measure the stellar seismic parameters, particularly for solar-like pulsators. Among them, red giant stars exhibit complex spectra showing pressure modes as well as mixed modes. The latter are a result of waves that behave as pressure waves in the star envelope and gravity waves in their core allowing to probe the core of these objects. The very high quality of the Kepler data enable us to decipher the complex structure of the mixed-mode pattern and, therefore, deduce precise informations on the structure of the stellar core. One of them concern the structural discontinuities present in the core of the star: the so-called glitches. These phenomenons have indeed an influence on the gravity waves that propagate in this medium. During the talk, we will investigate the influence of these discontinuities on the mixed-mode frequencies, depending on the glitch position, amplitude and shape, and discuss on how it can be observed. Then, we will present a method which allow the characterization of the glitch by the precise measurement of the mixed-mode frequencies. We will apply the method on several stars and present an analysis of the results. Finally, the implications of the results on the physical processes producing the discontinuities will be developed. 36

39 Talks: Monday, 9th July Seismic cartography of white dwarfs stars from Kepler to TESS: what we can learn from it (Invited) N. Giammichele 1 S. Charpinet 1, G. Fontaine 2, P. Brassard 2, A. S. Baran 3 (1) Institut de Recherche en Astrophysique et Planetologie (IRAP), University of Toulouse, CNRS, CNES, France. (2) Department of Physics, University of Montreal, Canada. (3) Suhora Observatory and Krakow Pedagogical University, Poland. The era of space missions have been providing us with asteroseismic data of unprecedented quality for many pulsating stars, including white dwarfs stars. White-dwarfs represent the ultimate products of the evolution of more than 95% of all stars, and their internal constitution carries the imprints of several mechanisms that occur during past phases of stellar evolution. In particular, it is expected that the internal chemical stratification of a typical white dwarf is shaped, over time, by the still uncertain rate of the 12C(α,γ)16O thermonuclear reaction, by convection, semi-convection, overshooting, and by thermal pulses that occur primarily on the Asymptotic Giant Branch. Pulsating white dwarfs are the perfect tools to dive into the core of these stars by fully exploiting their seismic potential and unravel firm observational constraints on past physical processes. I will present the most recent results obtained from analyses of white dwarf pulsators from Kepler and K2 space missions, with prospects for TESS. 37

40 Talks: Monday, 9th July Insights in Binary Stellar Evolution from Kepler/K2 (Invited) Emily Leiner 1,2 (1) Department of Astronomy, University of Wisconsin, USA. (2) Center for Interdisciplinary Exploration and Research in Astrophysics, Northwestern University, USA. Optical color-magnitude diagrams (CMDs) of star clusters reveal large populations of stars that do not fall along standard isochrones, and thus are not evolving according to standard stellar evolution theory. The most numerous of these stars are the blue stragglers, stars brighter and bluer than the cluster turnoff that formed via binary evolution processes: mass transfer, stellar mergers, and collisions during dynamical encounters. Other non-standard stars are also found in clusters including evolved blue stragglers stars on or near the cluster giant branch, sub-subgiants found fainter and/or redder than the giant branch, and subturnoff blue stragglers that blend photometrically with typical main-sequence stars. Timeseries surveys like TESS and Kepler have opened the door to detecting and characterizing these binary evolution populations in new ways. In this talk, I will review recent results from a Kepler K2 study of the old (4 Gyr) open cluster M67 that has revealed these binary evolution products across the cluster CMD using a combination of rotation and asteroseismology. The result is a much more complete snapshot of the post-interaction binary population, and illustrates the diverse and significant impact binaries have on stellar populations. M67 is an exemplar cluster, but it is certainly not unique. In the Gaia era, time-series missions will be key to uncovering these populations in other clusters and in the field, and can provide fresh insights into binary evolution physics. 38

41 Talks: Monday, 9th July The Synergy Between Binary Stars and Asteroseismoloy: Tides and Mass Transfer Zhao Guo 1,2 Douglas R. Gies 2, Rachel A. Matson 1,3, Avi Shporer 4, Jim Fuller 4, Howard T. Isaacson 5, Antonio Garcia Hernandez 6, Zhanwen Han 7, Xuefei Chen 7 (1) Copernicus Astronomical Center, Polish Academy of Sciences. (2) Georgia State University. (3) NASA Ames Research Center. (4) Caltech. (5) UC Berkeley. (6) Universidade do Porto. (7) Yunnan Observatories, the Chinese Academy of Sciences. More than half of all stars are binaries, and binarity has a significant impact on the stellar oscillations which has not yet been studied in detail. Mass transfer is a crucial ingredient in the evolution of binary stars, and it is an indispensable step to produce various types of stars (e.g., Algols, subdwarf B-stars, X-ray binaries, Neutron Star binaries, etc.). However, the effect of mass transfer on stellar oscillations is essentially uncharted territory in asteroseismology. Recently, there have been discoveries of several new classes of pulsating stars which cannot be formed through single star evolution (e.g., the anomalous Cepheids and RR Lyrae stars, and the Blue Large Amplitude Pulsators, etc.). We show that the Slowly Pulsating B-stars (SPBs), Delta Scuti stars, Gamma Doradus stars, and Extremely Low-mass White Dwarfs (ELWD) (and their precursors) can be formed via binary star evolution with the stable-mass transfer. This is demonstrated by characterizing the fundamental parameters and pulsation properties of three Kepler Eclipsing Binaries (KIC , KOI-81, and KIC ). Tides can greatly influence or even excite stellar oscillations. The Kepler telescope has offered us an unprecedented sample of binary stars with Tidally Excited Oscillations (TEOs) ( 20% of the Kepler heartbeat stars). We show that the pulsation phases and amplitudes of TEOs in the eclipsing binary KIC can be modeled very well by the linear tidal theory. The non-orbital-harmonic TEOs, however, requires the knowledge of the non-linear tide, e.g., the 1st-order non-linear effect of three-mode coupling. We also show preliminary results of modeling TEOs for ten more heartbeat binaries with spectroscopic follow-ups from the Keck HIRES spectrograph. Post-mass-transfer Pulsating Zoo 39

42 Talks: Monday, 9th July Binary Asteroseismology - Simultaneous and Independent Constraints ( and Headaches ) C. Johnston 1 A. Tkachenko 1, C. Aerts 1,2 (1) Institute of Astronomy, KU Leuven, Leuven, Belgium. (2) Department of Astrophysics, IMAPP, Radboud University, Nijmegen, The Netherlands. In recent years, asteroseismology of stars born with convective cores has revealed the importance of accounting for mixing, due to convective core overshooting, rotation, and element transport in stellar evolutionary codes. By modeling the deviations from regular periodspacing patterns in B- and F-stars pulsating in gravity modes, asteroseismic modeling has been able to determine near core rotation, as well as the size of the overshooting region in 60 F-type and 10 B-type stars. As these mixing phenomena directly regulate the amount of hydrogen available to the core for nuclear burning, calibrating and constraining their implementation in modern stellar structure and evolution codes is of paramount importance. However, asteroseismic modeling remains a largely model-dependent field prone to degeneracies and uncertainties in stellar interior physics. In this talk, we aim to mitigate these degeneracies through independent cross-calibration simultaneously performing isochrone fitting and forward asteroseismic modeling of Kepler gravity-mode pulsators in close binary systems. This enables us to enforce stringent constraints on dynamic quantities and initial metallicity, as well as impose an entirely independent assessment of stellar age. We answer the following pertinent questions of stellar evolution theory: 1) do results from binary and asteroseismic modeling agree? ; 2) what is the mass-dependence of the core overshooting?; 3) does binary interaction require serious deviation from asteroseismic modeling methodology for single stars? 40

43 Talks: Monday, 9th July Rogue waves from parametric resonance in pulsating white dwarfs J. J. Hermes 1 (1) Hubble Fellow, University of North Carolina at Chapel Hill, USA. The Kepler space telescope has uniquely enabled the discovery of what appears to be a new phase of stellar evolution: a state of recurrent nonlinear mode coupling in which energy is easily and rapidly transferred from excited pulsation modes to modes that are not standing waves but rather break at the surface of the star. These resonances, which recur chaotically, temporarily heat up the stellar surface by hundreds of degrees. I will discuss these white dwarf outbursts which have been observed in more than a dozen white dwarfs by K2 and appear confined to a narrow range of effective temperature centered around the most extreme example of this behavior in what happens to be the brightest pulsating white dwarf observed from space. I will also preview how TESS should deepen our understanding of this phenomenon. 41

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46 Talks: Tuesday, 10th July One Telescope, Two Missions, Thousands of Exoplanets (Invited) S. E. Thompson 1 (1) Space Telescope Science Institute, Baltimore, MD USA. The Kepler telescope, by searching for transits in the light curves of stars, has shown that exoplanets are common throughout our Galaxy and can be found around a variety of stars. The original Kepler mission stopped taking data in 2013, but the mission continued to improve its planet hunting algorithms and data characterization. In 2017, the Kepler mission left behind a final catalog of exoplanets along with tools to aide in understand the biases in the data for those measuring the occurrence rates of small, long-period planets. I will discuss this final catalog and some of the challenges in obtaining a definitive answer for those most like the Earth. While Kepler worked on this final survey catalog, the Kepler telescope continued to take data along the ecliptic. However, this K2 mission put guest observers in the driver s seat. As a result, one of K2 s contributions to exoplanet discovery has been in the diversification of the hunt. The stars chosen for exoplanet searches include brighter stars, nearby M-dwarfs, white dwarfs and giant stars. In this way K2 has probed the evolution of exoplanets by studying exoplanets around stars that are both young and old. Also, it has found exoplanets around small or bright stars that are more easily characterized with followup observations. I will highlight the importance of some of these discoveries, especially as astronomers set their sights on atmospheric characterization. 44

47 Talks: Tuesday, 10th July Stellar Activity and its Impact on Exoplanets (Invited) C. Garraffo 1 J. J. Drake 1, J. D. Alvarado-Gomez 1, S. P. Moschou 1, O. Cohen 1,2 (1) Harvard-Smithsonian Center for Astrophysics. (2) University of Massachusetts Lowell. Our knowledge of exoplanets is poised for a major leap forward with the recent launch of TESS and the impending launch of JWST, combined with the steady increase in groundbased capabilities. TESS will discover nearby exoplanets amenable for detailed study. JWST will probe exoplanet atmospheres and chemistry. Increasingly sophisticated ground-based observations are now able to measure absorption by important molecules in exoplanet atmospheres. M Dwarfs are the most feasible targets for finding planets orbiting on their habitable zone (HZ), since they are the most abundant stars in the galaxy ( 70%) and because their habitable zone resides very close to the star. However, M Dwarfs are very active stars and these close in planets will be exposed to much stronger magnetic activity effects than those we experience on Earth. It is now recognized that energetic stellar photon and particle radiation evaporates and erodes planetary atmospheres and controls upper atmospheric chemistry. In this talk I will discuss how such close-in planets can be exposed to strong dynamic pressure from the stellar wind, to fast variations of this pressure over timescales of days, and to energetic particles constantly precipitating on to the atmosphere. This extreme regime poses a new threat to atmospheric survival of close-in planets around active stars, like Proxima Centauri and TRAPPIST-1, and around stars that went through an active phase, like ROSS

48 Talks: Tuesday, 10th July A new spin on age-rotation-activity relations with Kepler and TESS T. S. Metcalfe 1 J. L. van Saders 2 (1) Space Science Institute, Boulder Colorado, USA. (2) University of Hawaii, Honolulu Hawaii, USA. The Kepler mission dramatically changed our understanding of how rotation and magnetism evolve in sun-like stars. Rotation in the open clusters with ages up to 2.5 Gyr agreed with prior expectations of stellar spin-down, but field stars with asteroseismic ages revealed a very different behavior. Beyond middle age, the angular momentum of stars no longer appeared to decrease over time, possibly due to a shutdown of magnetic braking (van Saders et al 2016). Ground-based spectroscopy of the older stars revealed that chromospheric activity continues to decrease with age, even while the rotation period remains almost constant (Metcalfe et al. 2016). For stars with known magnetic activity cycles, this transition appears to be accompanied by a gradual lengthening of the cycle before it eventually becomes undetectable or disappears entirely (Metcalfe & van Saders 2017). The TESS mission will soon provide additional tests of this scenario, by yielding asteroseismic masses and ages for stars observed for decades by the Mount Wilson survey. We will review the evidence for our new theory of magnetic evolution, and discuss future observational tests with the potential to radically transform age-rotation-activity relations. 46

49 Talks: Tuesday, 10th July Modelling Doris frequency shifts The impact of large-scale magnetic fields on stellar oscillation frequencies R. Kiefer 1 A.-M. Broomhall 1, T. Metcalfe 2,3, A. R. G. Santos 2 (1) University of Warwick, Coventry, UK. (2) Space Science Institute, Boulder, USA. (3) MPS, Göttingen, Germany. Temporal variations of stellar acoustic mode parameters, which are proxies for the level of stellar magnetic activity, can be measured from long-baseline photometric timeseries from space missions such as CoRoT, Kepler, and, in the future, TESS. With the theoretical framework presented by Kiefer et al. (2017) and Kiefer and Roth (2017), we carry out forward calculations of the perturbation of the p-mode frequencies of the star KIC (Doris / HD ). This star is of particular interest, as it is a solar analog regarding radius, mass, and age with the only significant differences being its metallicity, which is about twice the solar value, and its high level of magnetic activity (Karoff et al. 2018). We calculate the frequency perturbations of l = 0, 1 modes for a grid of magnetic field models (over toroidal magnetic field models with varying magnetic field strengths, depths of the peak strength, widths of the field concentration, and Gaussian or radially confined field topology). We compare these perturbations to Doris frequency variations as measured from two 90-day segments of Kepler data which are about three years apart (Santos et al., submitted). From this, we find that a magnetic field which is concentrated in the outer few percent of the star best reproduces the measured frequency shifts. Our results highlight the potential of an extended TESS mission to constrain internal stellar magnetic fields if the stars are revisited after a suitable length of time and the level of magnetic activity has changed along the stellar cycles. 47

50 Talks: Tuesday, 10th July Toward Stellar Butterfly Diagrams M. B. Nielsen 1 L. Gizon 2,3,1 (1) Center for Space Science, New York University Abu Dhabi, UAE. (2) Solar and Stellar Interiors Department, Max Planck Institute for Solar System Research, Germany. (3) Institute for Astrophysics, Georg-August Universität Göttingen, Germany. An important indicator of the solar magnetic activity cycle is the change in emergence latitudes of sunspots, leading to the well-known butterfly diagram. The corresponding phenomenon in other stars is poorly understood since starspot latitudes are generally unknown. Rotation rates from starspots are, however, comparatively easy to measure. Here we study an ensemble of 3091 Kepler stars for variations in rotation rate over the course of their magnetic activity cycles, which has been measured previously using photometric variability. We find that the spot rotation rate is generally anti-correlated with the activity cycle, similar to what is seen in the latter part of the solar activity cycle. The degree of anti-correlation is greatest for stars with rotation periods close to that of the Sun. On the other hand, both fast and very slow rotators on average show almost complete decorrelation between their measured spot rotation rate and their activity level. Furthermore, for solar-like rotators the variation in rotation rate begins to show an asymmetry between the start and end of the activity cycle, similar to what is seen from the solar butterfly diagram. 48

51 Talks: Tuesday, 10th July Prospects for exoplanet research with TESS (Invited) Benjamin T. Montet 1 (1) Depart of Astronomy and Astrophysics, University of Chicago, USA. The NASA TESS mission will provide light curves for nearly all bright stars across the entire sky, ushering in a new era for asteroseismology. In addition to this work, these light curves will also be useful for the detection and characterization of transiting planets. In this talk, I will provide an overview of some of the exoplanet research that will be enabled by the TESS mission. I will highlight some of the unique aspects of the TESS survey that will enable science that could not be accomplished with Kepler data, some of the challenges that TESS data will provide and how teams are planning to navigate them, and also some of the opportunities that will be made possible through synergistic efforts between TESS and future missions such as JWST, CHEOPS, and eventually PLATO. 49

52 Talks: Tuesday, 10th July Detection of p-modes in low-snr data: Implications for exoplanet and stellar research H. Kjeldsen 1,2 M. S. Lundkvist 1,3, T. R. Bedding 1,4 (1) Stellar Astrophysics Centre. (2) Aarhus Universitet, Denmark. (3) Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Germany. (4) University of Sydney, Australia. Global asteroseismic parameters such as frequency separations - for a large number of stars will be one of the key measurements for the asteroseismology part of the TESS mission. In the present talk we will discuss the techniques we plan to use to extract those parameters in a large number of stars observed by TESS at a relative low-snr due to the low amplitude of the p-mode oscillations. We will also address the implications for studies of exoplanets and stellar evolution based on the rich asteroseismic data set. In the present talk we will especially focus on measurements of accurate properties for exoplanets that might allow us to describe the structure and evolution of the hot super-earth and hot rocky exoplanets. This is part of a project to study and model the physical processes that affect the different types of exoplanets. The time series analysis is based on data from Kepler and in the talk we will use those data to discuss how one can run automated pipeline analysis to extract stellar parameters from time series space data for thousands of stars obtained by use of the TESS mission. Figure from Lundkvist, M. S., Kjeldsen, H., Albrecht, S. et al., 2016, Hot super-earths stripped by their host stars, Nature Communications, 7, id

53 Talks: Tuesday, 10th July Eccentricities and occurrence of planets around oscillating red giants with K2 S. Grunblatt 1 D. Huber 1, E. Gaidos 2, E. Lopez 3 (1) Institute for Astronomy, University of Hawaii. (2) Department of Geology and Geophysics, University of Hawaii. (3) NASA Goddard Space Flight Center. Understanding the properties of planets around giant stars is a complex yet important step in understanding the evolution of planetary systems and habitability in our Galaxy. Since 2016, I have been leading a search for giant planets orbiting low luminosity red giant branch (LLRGB) stars with K2. This search takes advantage of the unique synergy between asteroseismology and transit analysis to obtain precise stellar and planet parameters. Here, I present robust masses and radii of 5000 LLRGB stars, as well as two inflated, close-in planets on moderately eccentric orbits discovered by this survey. Furthermore, I demonstrate the first evidence that close-in giant planets orbiting red giant stars tend to reside on eccentric orbits, as well as constraints on the occurrence of close-in giant planets around LLRGB stars. Extending these results with TESS will uncover a more detailed view of this stellar and planet population and constrain the timescale for theories of planetary orbital evolution, disruption and engulfment. 51

54 Talks: Tuesday, 10th July TESS Data Preparation (Invited) M. N. Lund 1 R. Handberg 1, members T DA 2 (1) Stellar Astrophysics Centre (SAC), Aarhus University, DK. (2) Schools of Physics and/or Astronomy, Universities of Everywhere, Planet Earth. With data from the Transiting Exoplanet Survey Satellite (TESS) the seismic community is faced with a new set of challenges concerning the preparation of data. The TESS Asteroseismic Science Operations Center (TASOC) is tasked with delivering light curves ready for asteroseismic analysis to the TESS Asteroseismic Science Community (TASC) for each target observed by TESS. This includes the extraction of data from full-frame images (FFIs), correction of light curves, and stellar classification. In this talk, I will present the current status of the preparations for the delivery of photometric data products within the TASC Coordinated Activity 1. 52

55 Talks: Tuesday, 10th July FliPer: A new method to rapidly estimate surface gravities with high precision from main sequence to late red giants (0.1 < logg < 4.6 dex) L. Bugnet 1,2 R. A. García 1,2, G. R. Davies 3,4, S. Mathur 5,6,7, E. Corsaro 8, O. J. Hall 3,4, B. M. Rendle 3,4 (1) IRFU, CEA, Université Paris-Saclay, F Gif-sur-Yvette, France. (2) Université Paris Diderot, AIM, Sorbonne Paris Cité, CEA, CNRS, F Gif-sur-Yvette, France. (3) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. (4) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (5) Instituto de Astrofísica de Canarias, E-38200, La Laguna, Tenerife, Spain. (6) Universidad de La Laguna, Dpto. de Astrofísica, E-38205, La Laguna, Tenerife, Spain. (7) Space Science Institute, 4750 Walnut Street Suite 205, Boulder, CO 80301, USA. (8) INAF - Osservatorio Astrofisico di Catania, Via S. Sofia 78, I Catania, Italy. Stellar parameters such as mass, radius and surface gravity are the key to understanding stellar evolution. They are usually provided by Asteroseismology through the use of global seismic parameters (the frequency of maximum power and the large frequency spacing). However, only stars showing acoustic oscillation mode patterns in their power density spectra can be studied with this seismic methodology through global seismic pipelines. Seismicindependent methods are now being developed in order to estimate the surface gravity for stars with solar-like oscillations. It includes main-sequence stars for which the oscillation modes are not visible in the spectra because they oscillate with a frequency higher than the the Kepler long-cadence mode Nyquist frequency of the observations. We present here a new metric called FliPer (Flicker in Power) that directly measures the global power in the spectra in opposition to the Flicker method computed in the time domain. Our method exploits the use of a Random Forest machine learning algorithm that takes into account FliPer values and effective temperatures to give an estimation of surface gravity. The algorithm is trained on a sample of oscillating main-sequence and red-giant stars with surface gravities ranging from 0.1 to 4.6 dex, as obtained with the A2Z global asteroeismic pipeline. Once trained, the regressor can be applied to any main-sequence and red-giant star, including bright red giants, extending the lower limit of the determinable surface gravity range down to 0.1 dex (in contrast to the surface gravity lower limit of 2.5 dex obtained using Flicker) without needing any additional seismic analysis. Typical uncertainties on our surface gravities are no larger than 0.1 dex, and are even smaller depending on the evolutionary state of the star. 53

56 Talks: Tuesday, 10th July Using Gaussian Processes to model granulation and oscillations in red-giant stars L. F. Pereira 1,2 T. L. Campante 1,2, M. S. Cunha 1,2, N. C. Santos 1,2 (1) Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, CAUP, Rua das Estrelas, PT Porto, Portugal. (2) Departamento de Física e Astronomia, Faculdade de Ciências, Universidade do Porto, Rua do Campo Alegre, PT Porto, Portugal. The analysis of photometric time series in the context of transiting planet surveys suffers from the existence of stellar signals, often dubbed noise. These signals, namely, stellar oscillations and granulation, can usually be disregarded for main-sequence stars, as the stellar contributions average out when phase-folding the light curve. For evolved stars, however, the amplitudes of the signals are larger and the timescales are similar to the transit duration of short-period giant planets, requiring that they be modeled alongside the transit. With the promise of TESS delivering of the order 10 5 light curves for stars along the redgiant branch, there is a need for a method capable of describing such stellar noise while simultaneously searching for an exoplanet transit. We introduce the theoretical framework of Gaussian Process regression and validate our method by applying it to TESS-like artificial data. Furthermore, we characterize the stellar oscillations and granulation of 19 Kepler lowluminosity red-giant branch stars. We consider subsets of 27.4 days of observations from the complete Kepler time series in order to simulate the typical amount of data expected from TESS for a single star. The parameters found are compared to equivalent parameters obtained by modeling the power spectrum of those same data subsets. Results show that not only are Gaussian processes capable of describing the stellar signals in the time domain, the method can also recover a very precise measurement of ν max, in close agreement with the values obtained in the power spectrum fitting. 54

57 Talks: Tuesday, 10th July GYRE: A Stellar Oscillation Toolkit for the TESS Era Rich Townsend 1 (1) Department of Astronomy, University of Wisconsin-Madison, Madison, WI 53706, USA. GYRE is a software instrument for modeling stellar oscillations and related phenomena. It solves the linear, non-radial, non-adiabatic pulsation equations to evaluate the eigenfrequencies and corresponding eigenfunctions of an input model star. It understands models produced by a variety of stellar evolution codes, and is especially optimized to work with the widely adopted MESA code. GYRE makes efficient use of parallel computer hardware, supports the Linux and Mac OS operating systems, and is freely available under an open-source license. In this presentation, I ll briefly review the basic operation and features of GYRE. I ll then showcase its successfull application, by a vibrant and growing worldwide user community, to analyzing and interpreting a smörgåsbord of phenomena: solar-like oscillations in mainsequence, sub-giant and red-giant stars; heat-driven oscillations in β Cephei, γ Doradus, δ Scuti, and slowly-pulsating B stars; and oscillations excited by other processes such as the epsilon mechansim in supersoft sources, and tidal forces in binary systems. TESS will provide unprecedented observations of many of these phenomena, and GYRE stands ready to leverage these observations into detailed astroseismic analyses for individual targets, and into ensenble analyses (including instability-strip mapping) for entire populations of targets. To finish my presentation, I ll discuss recent improvements to GYRE made in anticipation of TESS s launch, that will enable and enrich these activities. 55

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60 Talks: Wednesday, 11th July Interferometry and asteroseismology (Invited) T. R. White 1 (1) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. Interferometry and asteroseismology are both powerful techniques that allow us to measure stellar properties with unprecedented precision, advancing understanding of stellar structure and evolution, and informing branches of astronomy from exoplanetary science to Galactic archaeology. But how well can we trust these techniques? The space photometry revolution, instigated by the CoRoT and Kepler missions, has resulted in the detection of oscillations in thousands of stars across the HR diagram, but only a few dozen that are bright enough to be followed-up with interferometry. These few stars provide an opportunity to pit these powerful methods against each other, and thereby drive new insights. I will review the current efforts to validate asteroseismic methods using interferometry, how their combination is leading to tests and improvements of stellar models, and future prospects with TESS and the next generation of interferometric instrumentation. 58

61 Talks: Wednesday, 11th July Realistic modeling of stellar surfaces for better asteroseismic frequencies. (Invited) L. Bigot 1 (1) Laboratoire Lagrange, Observatoire de la Côte d Azur. It is known for a long time that our best stellar evolution codes lead to a systematic overestimate of the calculated oscillation frequencies in solar-like stars. This effect that increases with the frequency is the so-called «surface effect». It reflects the complex physical processes at work in the surface layers of the star which are not, or poorly, taken into account in standard stellar evolution and oscillation codes. The computed frequencies are shifted for mainly two reasons. The first one is the simplified treatment of convection. This causes the «structural» contribution to the surface effect. The second one is the simplified modeling of the mode physics itself, in particular the absence of nonadiabaticity and coupling with convective motions in standard pulsation codes. This causes the «modal» contribution to the surface effect. This surface effect needs to be corrected to have reliable asteroseismic diagnostics. One way to do it consists in using realistic 3D time-dependent radiative hydrodynamical simulations of the stellar surfaces and include horizontal averages into standard 1D stellar evolution codes. It is now possible to do it in a quasi-systematic way since grids of 3D models exist and cover the range of fundamental parameters of solar-like stars. Correction of the modal effect can be done thanks to the non-local mixing length formalism and needs to be added to obtain the total surface effect. In this talk I will review the efforts made during the last years to improve the modeling of the surface layers of the Sun and stars and discuss the consequences for oscillation frequencies. 59

62 Talks: Wednesday, 11th July Precise radii from the signature of granulation M. S. Lundkvist 1,2 H. Kjeldsen 2, G. R. Davies 3,2, H.-G. Ludwig 1, W. J. Chaplin 3,2 (1) Zentrum f` ur Astronomie der Universit at Heidelberg, Landessternwarte, Germany. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. (3) School of Physics and Astronomy, University of Birmingham, UK. We present a novel method for obtaining stellar radii using the granulation background for both giants and main-sequence stars observed by Kepler and K2. The method is based on a simple scaling using the effective time scale and the frequency integral of the granulation signal in combination with the effective temperature. In this presentation, we demonstrate the performance of the method using a subsample of stars with radii determined from asteroseismology. Although the employed scaling relation is data-driven, we investigate what can be learnt from incorporating expectations from 3D hydrodynamical simulations into the relation. Interestingly, we find that our simple scaling with only small modifications reproduce the asteroseismic radii better than a scaling relation based on 3D simulations. Finally, we discuss the extension and applicability of this method to the TESS mission and reflect on the usefulness of this tool in light of Gaia DR2. 60

63 Talks: Wednesday, 11th July Using 3D hydrodynamics simulations on-the-fly for stellar evolution calculations J. R. Mosumgaard 1,2 A. C. S. Jørgensen 2 (1) Stellar Astrophysics Centre, Aarhus University, Denmark. (2) Max Planck Institute for Astrophysics, Garching, Germany. The nuclear timescales that govern the evolution of stars are much longer than the timescales associated with stellar convection, which is extremely important for low-mass stars and solar-like oscillators. This necessitates the use of a simplified parametrization namely the mixing-length theory to describe convection in stellar evolution calculations. However, we know from asteroseismology that current stellar models do not reproduce the correct structure of the outermost layers of stars with convective envelopes. In order to account for this shortcoming and to improve our stellar structure models, we have employed the results from sophisticated 3D hydrodynamic simulations, following several different approaches. One of these methods amounts to substituting the outermost layers of the model with a mean 3D stratification at a given evolutionary stage. For the Sun, this so-called patched model leads to better agreement with the observed oscillation frequencies. We have also applied the patching techique to several main-sequence stars from Kepler. As a second approach, we have used a boundary condition derived from the 3D simulations in the evolution code, as well as calibrated the mixing-length convection in the model to the same simulations. This has the advantage, that it is possible to include 3D results in the evolution, but the impact is not nearly as strong as for the patched models. Thirdly, we are working on a combination of the two methods: using the full 3D hydro simulations on-the-fly, which has never been attempted before. Including the entire mean 3D stratification in the evolution calculation itself will greatly improve on the inherent inconsistencies of patched models, as well as resulting in better evolutionary sequences. Hopefully this method will be able to provide the next generation of physically accurate stellar models, and is a major goal in the quest for more realistic stellar evolution. 61

64 Talks: Wednesday, 11th July Dependence to surface gravity and temperature of p modes asymmetry in Sun-like stars observed by Kepler O. Benomar 1 Mjo. Goupil 2, K. Belkacem 2, T. Appourchaux 3, M. B. Nielsen 1, M. Bazot 1, L. Gizon 1,4,5, S. Hanasoge 1,6, K. R. Sreenivasan 1,7, B. Marchand 1 (1) NYUAD Institute, Center for Space Science, New York University Abu Dhabi, P.O. Box , Abu Dhabi, UAE. (2) LESIA, UMR8109, Université Pierre et Marie Curie, Université Denis Diderot, Obs. de Paris, F-92195, Meudon Cedex, France. (3) Univ. Paris-Sud, Institut d Astrophysique Spatiale, UMR 8617, CNRS, Bâtiment 121, F , Orsay Cedex, France. (4) Max-Planck-Institut für Sonnensystemforschung, D Göttingen, Germany. (5) Institut für Astrophysik, Georg-August-Universität Göttingen, D Göttingen, Germany. (6) Tata Institute of Fundamental Research, Mumbai, , India. (7) New York University, NY 10012, USA. The p modes seen in Sun-like pulsators are usually analysed by fitting the power spectrum with a sum of symmetric Lorentzian line profiles. This profile is found by considering each mode as a stochastically excited damped oscillator, with an non-localized excitation source at the surface of the star. However, solar observations (Duval et al. 1993) show that p-mode line profiles are asymmetric Lorentzians. This indicates that the p modes excitation occurs mostly at a given depth inside the Sun. Here, we investigate the asymmetry of Lorentzian mode profiles for 43 stars observed in photometry by Kepler. We find that the asymmetry parameter strongly depend on surface gravity log(g) and on effective temperature T eff. Stars with log(g)< 4.35 and T eff > 5800 K show modes with negative asymmetry (skewed toward low frequency), while those with higher log(g) and lower T eff have a positive asymmetry. We also show that the sign reversal happens gradually in the HR diagram. The mode asymmetry could be important in order to measure accurately the pulsations frequencies used for constraining stellar models. It is also of fundamental importance to understand the convection and the mechanism of excitation and damping of acoustic waves in Sun-like stars. 62

65 Talks: Wednesday, 11th July Galactic archaelogy with Kepler, APOGEE and Gaia (Invited) M Martig 1 (1) Astrophysics Research Institute, Liverpool John Moores University, UK. I will describe some of our recent efforts to map the structure of the Milky Way, with a particular emphasis on the nature of the thick disk and comparisons with predictions from cosmological simulations. I will show how we combined APOGEE spectra with Kepler data to determine ages for a large sample of stars in the Milky Way, and how 6D phase-space information from Gaia DR2 sheds light on the kinematics of stars of different ages. 63

66 Talks: Wednesday, 11th July APOKASC-2: How well can we measure masses from asteroseismology? Marc H. Pinsonneault 1 (1) Ohio State University, Dept. of Astronomy, USA. Asteroseismology has tremendous potential as a tool for stellar physics and stellar populations. The process of inferring masses and ages using asteroseismology involves a complex series of tasks on matters ranging from how the oscillations are characterized to how (or whether) the stellar parameters are calibrated. To realize this potential we must critically examine all of our assumptions. I present the results from APOKASC-2, which is an empirical approach to the problem of asteroseismic masses and ages. APOKASC-2 is a sample of almost 7,000 cool giants with APOGEE and KASC data in the Kepler field. I emphasize the importance of employing multiple analysis methods, moving beyond simple scaling relations, and calibration of the derived stellar properties against fundamental quantities. In the best cases low luminosity first ascent giants random and systematic mass errors are at the 4% level, with significantly larger uncertainties for core He-burning stars and luminous first ascent giants. The distribution of uncertainties is quite different from prior error models. I close by discussing the complementary roles of Gaia and asteroseismology, what needs to be done to break through to higher levels of precision, and on the strengths and drawbacks of grid-based modeling approaches. 64

67 Talks: Wednesday, 11th July Characterising the Vertical Structure of the Milky Way with K2 B. M. Rendle 1,2 A. Miglio 1,2, E. Elsworth 1,2, R. A. Garcia 3, S. Mathur 4, B. Mosser 5, M. N. Lund 2,1, G. Davies 1,2, C. Chiappini 6,7, M. Valentini 6, P. Jofre 8, C. C. Worley 9, L. Girardi 10,7, N. Legarde 11, A. Robin 11, C. Reyle 11 (1) School of Physics and Astronomy, University of Birmingham, Edgbaston, B15 2TT, UK. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C Denmark. (3) Laboratoire AIM, CEA/DSM CNRS - Univ. Paris Diderot IRFU/SAp, Centre de Saclay, Gif-sur-Yvette Cedex, France. (4) Space Science Institute, 4750 Walnut Street, Suite 205, Boulder, Colorado 80301, USA. (5) LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Pierre et Marie Curie, Université Paris Diderot, Meudon, France cedex, France. (6) Leibniz-Institut für Astrophysik Potsdam (AIP), An der Sternwarte 16, Potsdam, Germany. (7) Laboratório Interinstitucional de e-astronomia, LIneA, Rua Gal. José Cristino 77, Rio de Janeiro, Brazil. (8) Núcleo de Astronomía, Facultad de Ingeniería, Universidad Diego Portales, Av. Ejército 441, Santiago, Chile. (9) Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA, UK. (10) Osservatorio Astronomico di Padova INAF, Vicolo dell Osservatorio 5, Padova, Italy. (11) Institut UTINAM, CNRS UMR 6213, Univ. Bourgogne Franche-Comté, OSU THETA Franche- Comté-Bourgogne, Observatoire de Besancon, BP 1615, Besancon Cedex, France. We present here the initial findings of the K2 Galactic Poles Project, a collaboration designed to investigate the vertical properties of the Milky Way through the combination of high precision asteroseismic and spectroscopic data. The vertical structure of the Milky Way and the nature of its disc-like components remain one of the unsolved problems surrounding the formation of our galaxy. Largely concentrating on whether the galactic disc contains multiple components (i.e. a thin and thick disc), or is a singular, continuous entity, multiple studies have put forth evidence to support both situations without one argument conclusively outweighing the other. Exploiting the unique opportunities presented to us by K2 observations of red giants towards the galactic poles, we demonstrate the potential K2 has to characterise (and improve upon) vertical population trends and how it can provide further assistance to definitively answering the questions surrounding the galactic disc(s). In particular, we highlight the improvements in age determinations through asteroseismology and the subsequent inferences about the star formation history of vertical populations that can be made. 65

68 Talks: Wednesday, 11th July Young alpha-rich stars: the view from K2 Jennifer Johnson 1 (1) Department of Astronomy, Ohio State University, USA. Stars with unexpectedly young ages for their chemical composition have been detected in the Kepler and CoRoT fields. While some of these stars undoubtedly owe their high masses to mass transfer from a companion, some may represent a population with a distinct chemical evolution history that have been radially mixed into the solar circle. In this work, we examine the distribution of this high [alpha/fe] high-mass population in the K2 fields, which probe the Galaxy along different lines of sight than the Kepler or CoRoT fields. By examining the frequency and kinematics of these stars, we will address the question of their origin and of the location of possible reservoirs of such stars in the Galaxy. 66

69 Talks: Wednesday, 11th July Developing AI Experts in Asteroseismology with Deep Learning M. Hon 1 D. Stello 1,2,3 (1) School of Physics, The University of New South Wales, Sydney NSW 2052, Australia. (2) Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia. (3) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. Deep learning is a specialized form of machine learning that is considered an approach to artificial intelligence. By drawing inspiration from biological nervous systems, deep learning is capable of automatically capturing rich and abstract patterns or representations in data, giving it an edge over conventional machine learning methods. This has allowed it to achieve great success in a variety of complex applications such as image recognition, language translation, and speech recognition, making this a promising analysis tool for asteroseismic research. In my talk, I will introduce the concept of using deep learning in asteroseismology in the form of computer vision to classify asteroseismic frequency power spectra, where my recent applications on K2 and TESS-like data involve (1) the detection of solar-like oscillations with a near human expert-level performance, and (2) the classification of the evolutionary states of red giants with a higher level of accuracy than the human expert. The high efficiency shown by these methods further add evidence that the use of deep learning can be very useful in extracting important information from the high volume of time-resolved data from the K2, TESS, and PLATO missions. 67

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72 Talks: Thursday, 12th July Prospects for Galactic Archeology with time-domain data (Invited) M Ness 1,2 (1) Department of Astronomy, Columbia University, Pupin Physics Laboratories, New York, NY 10027, USA. (2) Center for Computational Astrophysics, Flatiron Institute, 162 Fifth Avenue, New York, NY 10010, USA. The numbers of both spectroscopic and photometric time-domain observations of stars have increased by many orders of magnitude over the last few years. Ground-based spectroscopic surveys now observe on the order of 10 5 to 10 6 stars, obtaining measurements of stellar temperatures, gravities and surface chemical compositions ([Fe/H], [X/Fe]). Concurrently, time-domain surveys operating at high cadence over long baselines have observed on the order of a few 10 5 stars. From the combination of spectroscopic and time-domain photometric data, we are assembling an inventory of information about stars, linking stellar chemical compositions and dynamics to stellar age, variability and structure. Numerous future multiepoch photometric missions (e.g. TESS and PLATO) plus spectroscopic surveys, e.g. 4- MOST, MOONS and Sloan-V, and - the landscape changing Gaia mission - will soon deliver data volumes far exceeding our current inventory. I will present some examples of how we can combine this inventory of information, so as to understand the large scale processes that have driven the formation of our Galaxy. 70

73 Talks: Thursday, 12th July Gaia: mission status and the second data release (Invited) A. G. A. Brown 1 (1) Leiden Observatory, Leiden University, Netherlands. I will present an update of the Gaia mission status with a focus on the plans for a mission extension and the future Gaia data releases. This is complemented by a summary of Gaia s second data release and a few highlights from the first science harvested from Gaia DR2. 71

74 Talks: Thursday, 12th July Mixing in Red Giants: The [C/N] Ratio Jamie Tayar 1 Matthew Shetrone 2, Jennifer Johnson 1, Garrett Somers 3, Marc Pinsonneault 1 (1) Ohio State University, Department of Astronomy, USA. (2) University of Texas at Austin, McDonald Observatory, USA. (3) Vanderbilt University, Department of Physics and Astronomy, USA. Mixing signals serve as a precise diagnostic of the conditions of the stellar interior. With the combination of elemental abundances from spectroscopy and asteroseismology from the Kepler mission, it is now possible to quantitatively compare the predictions of stellar models to observations as a function of mass and metallicity. Using the carbon to nitrogen ratio, I will show that at solar metallicity, simple models accurately predict the depth of the first dredge up as a function of stellar mass. However, I will also show significant discrepancies between simple models of mixing and observations in the metal poor domain. I will demonstrate the need for a metallicity dependent mixture of elements. Finally, I will quantify the smooth changes in the strength of extra mixing above the luminosity bump as a function of metallicity, which can be used to constrain more complex models of mixing. 72

75 Talks: Thursday, 12th July Ages and masses of metal poor stars M. Valentini 1 C. Chiappini 1, D. Bossini 2 (1) Leibniz-Institut für Astrophysik Potsdam (AIP). (2) INAF-Osservatorio Astronomico di Padova. Metal poor stars are key to understanding the history of our Galaxy. In their element abundances pattern is encoded the chemical composition of the first stars and therefore, when the stellar age is available, hints on the chemical enrichment and evolution of the Milky Way. However, obtaining precise ages for field metal poor stars is a challenging task: at present only an handful of very metal-poor stars have ages, derived by using nucleocosmo-chronology (via Thorium and Uranium abundances). Asteroseismology in recent years demonstrated to be a powerful tool to derive masses, and hence ages, of red giant stars. By applying this technique to metal poor stars we increased the number of metal poor objects with an age measurement. We present an exploratory set of 4 metal poor red giant stars ([Fe/H]<-1.5 dex) selected from RAVE survey. We obtained seismic information from the light curves collected by the K2 space mission, and detailed chemical abundances from ESO-UVES high resolution spectra. We derived the atmospheric parameters, by taking into account the seismic surface gravity. Chemical abundances were derived by taking into account NLTE effects. The final atmospheric parameters and abundances, together with the seismic information and, when available, Gaia parallaxes, were used for deriving stellar masses, radii and ages, via Bayesian fitting on a set of isochrones (PARAM tool). We obtained a unique set of metal poor stars, for which we determined precise ages. For the first time a consistent and complete approach have been adopted, in order to quantify the impact of temperature shifts, different mass-loss approaches, alpha-enrichment, the adoption of different seismic pipelines, and corrections to seismic scaling relations. This exploratory sample, obtained from the first K2 Campaigns, shows how it is possible to obtain precise ages for field metal poor giants. 73

76 Talks: Thursday, 12th July Testing asteroseismology with Gaia DR2: Position and membership of Red Clump stars O. J. Hall 1,2 G. R. Davies 1,2, Y. Elsworth 1,2 (1) School of Physics and Astronomy, University of Birmingham, B15 2TT, UK. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. Core Helium Burning stars of solar-like masses that go through the Helium flash have reasonably homogeneous luminosities, creating an overdensity of stars on a HR diagram the red clump. With astrometric and asteroseismic data we have two independent methods with which to determine the luminosity and spread of the red clump. Asteroseismic and astrometric methods should produce compatible estimates of the clump luminosity. Differences between the methods might be attributable to asteroseismic scaling relations, spectroscopic temperature scales, or bolometric corrections, among many others. We use asteroseismic scaling relations to calculate the luminosity of our target stars, and apply a colour correction to find the asteroseismic absolute magnitude in various passbands. Simultaneously, we use the Gaia DR2 parallax and colours, along with dustmaps, to calculate an astrometric absolute magnitude in these passbands. We apply a hierarchical Bayesian mixture model to both data sets, simultaneously finding the population level properties of the red clump in absolute magnitude. We will present the resulting differences between the asteroseismic and astrometric methods, as well as a thorough analysis of the origin of this discrepancy by considering multiple corrections to the asteroseismic scaling relations, spectroscopic temperature scales, and bolometric corrections. 74

77 Talks: Thursday, 12th July What exoplanet studies need from asteroseismology (Invited) W. J. Chaplin 1,2 (1) University of Birmingham, UK. (2) Stellar Astrophysics Centre, Aarhus University. In this invited talk I will review the ways in which results from asteroseismology feed into studies of exoplanetary systems. I will discuss various aspects of how this process is facilitated, both directly, from analysis conducted on individual host stars of interest; and indirectly, as a result of improvements made to our understanding of key aspects of stellar evolution theory and stellar interiors physics, and underpinning analysis and methodologies. My talk will have a heavy focus on upcoming and future opportunities, and associated challenges for the asteroseismology community. 75

78 Talks: Thursday, 12th July The Gaia Revolution of Kepler Stars: Implications for Asteroseismology and Exoplanets Daniel Huber 1,2,3 Travis Berger 1, Joel Zinn 4, Marc Pinsonneault 4 (1) Institute for Astronomy, University of Hawaii. (2) Sydney Institute for Astronomy, University of Sydney. (3) Stellar Astrophysics Centre, Aarhus University. (4) Department of Astronomy, Ohio State University. Gaia DR2 will include parallaxes measured to 10% or better for nearly all Kepler targets, providing an unprecedented sample to test the accuracy of stellar radii derived from asteroseismology over a wide range of evolutionary states. I will present first results of calibrating asteroseismic scaling relations for solar-like oscillators ranging from the main-sequence to the red-giant branch using Gaia DR2 parallaxes, including comparisons to results from Gaia DR1 and CHARA interferometry. I will furthermore present a first-look revision of stellar radii in the Kepler Stellar Properties Catalog using Gaia DR2, and discuss its implications for our understanding of Kepler exoplanet radii and occurrence rates. 76

79 Talks: Thursday, 12th July (1) Leiden University. An asteroseismic view of the radius gap V. Van Eylen 1 Almost everything we know about exoplanets has been inferred indirectly through their host stars, making it crucial to understand stars if one hopes to learn about planetary systems. Asteroseismology provides the current gold standard of stellar characterization. In this talk, I explain how asteroseismic studies provide important new insights into the formation and evolution of small close-in planets, which the TESS survey is expected to discover in large numbers. I show how asteroseismology can be used to detect and investigate the radius gap, which separates super-earths and sub-neptunes, with greater clarity than any other method - even allowing the determination of the exact location of the radius gap as a function of orbital period. This new measurement provides several key physical insights: 1) the slope of the radius gap is inconsistent with late gas-poor formation, but matches photo-evaporation models; 2) the complete lack of secure planet detections inside the gap is a result of homegeneous planet core compositions; and 3) these cores have a terrestrial composition, implying in situ formation rather than planet migration from beyond the ice line. I conclude by discussing the role asteroseismology can play for exoplanets in the TESS era. 4 3 R [R ] Orbital Period [d] 77

80 Talks: Thursday, 12th July Exoplanets Orbiting Asteroseismic Hosts: The Curious Case of KOI-4 A. Chontos 1 D. Huber 1,2, D. Latham 3, A. Bieryla 3, L. Buchhave 4, J. Coughlin 2,5 (1) Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI 96822, USA. (2) SETI Institute, 189 Bernardo Avenue, Suite 200, Mountain View, CA 94043, USA. (3) Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA. (4) Niels Bohr Institute, University of Copenhagen, DK-2100, Copenhagen, Denmark. (5) NASA Ames Research Center, Moffett Field, CA 94035, USA. Asteroseismology is one of the most precise methods to characterize exoplanet host stars, and hence provide precise fundamental properties of exoplanets. I will present the first complete asteroseismic study of all Kepler exoplanet hosts since the final release of short-cadence data. The results show 12 new detections, including Kepler s first planet discovery, KOI-4. KOI-4 was initially classified as a main sequence star hosting a Neptune-sized planet, which triggered a false positive classification based on the observation of a secondary eclipse. This seismic detection, coupled with TRES radial velocity measurements, demonstrates for the first time that the planet is in fact a massive hot-jupiter around an evolved subgiant. With an orbital period of less than 4 days, KOI-4 is now the closest known planet around an evolved star, making it a benchmark system to measure orbital period decay and test tidal dissipation. KOI-4 represents a typical example of seismic host stars that we expect to find with TESS. Since TESS is sensitive to our solar neighborhood, planets found by TESS will be more amenable to RV follow up, resulting in precise planet densities. 78

81 Talks: Thursday, 12th July Convection in massive stars: what can be learnt from hydrodynamics simulations and asteroseismology? (Invited) Cyril Georgy 1 Sylvia Ekström 1, Georges Meynet 1, Raphael Hirschi 2, Dave Arnett 3, Casey Meakin 3, Andrea Cristini 4, Hideyuki Saio 5 (1) Geneva University. (2) Keele University. (3) Arizona University. (4) Oklahoma University. (5) Tohoku University. In this talk, I will discuss the current shortcomings linked to the treatment of convection in massive star models. I will first discuss the actual way of dealing with convection and convective boundary mixing in stellar evolution codes, and show the impact of these various treatment in the outcomes of the models. I will then present recent results coming from high resolution hydrodynamics simulation of convection. I will compare our findings with constraints coming from asteroseismology. In a next step, I will show how combining various observational technics, such as asteroseismology and spectroscopy, can help in improving our understanding of convection in massive stars. To illustrate this, I will use the case of the α-cyg variables, discuss their evolutive status and show what can be learnt about the position of the convective shells from their properties. 79

82 Talks: Thursday, 12th July Evidence of global Rossby modes in many Kepler intermediate-mass main-sequence stars V. Antoci 1 H. Saio 2, D. W. Kurtz 3, S. Murphy 1,4, H. Shibahashi 5 (1) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (2) Astronomical Institute, Graduate School of Science, Tohoku University, Sendai, Miyagi , Japan. (3) Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK. (4) Sydney Institute for Astronomy, School of Physics, The University of Sydney, NSW 2006, Australia. (5) Department of Astronomy, The University of Tokyo, Tokyo , Japan. Over 100 Kepler stars, including the famous Tabby s Star, show a conspicuous hump with a spike features in their oscillation spectra. While it was conjectured that this signature could originate from differential rotational modulation induced by stellar activity as in the Sun coupled with reflection from exoplanets with short orbital periods (e.g. Balona 2017), reflection from exoplanets is not viable in these cases, and the differential rotation with many solar-like spots interpretation poses a some problems for stellar models, as the envelope structure of intermediate-mass stars cannot support magnetic activity. Recently, we have found an astrophysically robust theoretical explanation that the observed humps are due to Rossby waves (Saio et al., 2018), a physical phenomenon that is in good agreement with stellar structure models. We do associate the spike with rotational modulation, hence still need some surface spots to account for this. Such r-mode oscillations were previously suggested to exist in a few intermediate-mass stars (Van Reeth et al. 2016), but they have not been put in context with the hump with a spike features so far. In this talk we will give an introduction to Rossby waves and present our analyses of more than 100 stars that display this phenomenon, thereby showing that r-modes are relatively common in intermediate-mass stars. 80

83 Talks: Thursday, 12th July Model-independent measurements of gamma Dors internal rotation as a test of angular momentum transport models S. Christophe 1 R-M. Ouazzani 1, J. Ballot 2, J. P. Marques 3, M-J. Goupil 1, V. Antoci 4, S. J. A. J Salmon 5 (1) LESIA - Paris Observatory. (2) IRAP - Université de Toulouse. (3) IAS - Université Paris Sud. (4) SAC - Aarhus University. (5) STAR Institute, Université de Liège. Helioseismology and asteroseismology of red giant stars have shown that distribution of angular momentum in stellar interiors, and its evolution with time remain an open issue in stellar physics. Owing to the unprecedented quality and long baseline of Kepler photometry, we designed a new stellar-model-independent method to seismically infer internal rotation rates in gamma Doradus stars, which provide the main-sequence counterpart to the red giants puzzle. These intermediate-mass stars pulsate in high order gravity modes that probe the deep radiative layers near their convective-core. They are also moderate to fast rotators for which an appropriate treatment of the pulsation-rotation coupling is required to disentangle the oscillation spectrum. On the basis of the traditional approximation of rotation (TAR), we have developed a new method allowing to simultaneously estimate the near-core rotation frequency, the buoyancy travel time, and identify the gravity modes. Thorough tests on synthetic spectra were carried out to characterize the method and evaluate its performance as a tool to interpret observed oscillation spectra. The first part of this talk will present the main steps of the method, its limitations in the current implementation, and the possibilities it has to offer. In the second part, we will illustrate these possibilities by applying the method to numerous Kepler targets in order to obtain seismic constraints on models of angular momentum transport. To that end, we used rotating evolutionary models of intermediatemass stars including internal transport of angular momentum in radiative zones following the formalism developed by Zahn and Maeder. We show that the transport of angular momentum as formalized by Zahn and Maeder cannot explain the measurements of near-core rotation in main-sequence intermediate-mass stars we have at hand. 81

84 Talks: Thursday, 12th July Rotational splitting in δ Scuti stars: the hidden link A. García Hernández 1 A. Ramón Ballesta 1, J. C. Suárez 2 (1) Department of Theoretical Physics and Cosmology, University of Granada (UGR), Spain. (2) Valencian International University (VIU), Spain. Rotational splitting is one of the most wanted observables to be detected in the stellar oscillation spectrum. Up to now, only slow rotating cases or analysis of the g modes regime have succeded in finding it. In this work, we searched for the rotational splitting in δ Scuti stars belonging to an eclipsing binary system. We used two approaches: a Fourier transform of the frequencies and a histogram of frequency differences. The latter showed to be a better procedure. For the majority of the cases, we identified the splitting once the large separation is determined. This is the first time we may clearly state that one of the periodicities present in the p modes oscillation spectra of delta Scuti stars corresponds to the rotational splitting. This is true independently of the stellar rotation rate. Here we show some results as compared with rotating models too. These promising results pave the way to find a robust methodology to determine rotational splittings from the oscillation spectra of delta Scuti stars. 82

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86 Talks: Friday, 13th July Highlights in the variability of OB stars from Kepler/K2 and prospects for TESS (Invited) C. Aerts 1,2 (1) Institute of Astronomy, KU Leuven, Belgium. (2) Radboud University Nijmegen, the Netherlands. Since the start of the space age of asteroseismology, tremendous progress has been made in the understanding of stellar structure and evolution. In this talk, we provide recent highlights in the detection and interpretation of OB-type star variability. Such massive stars were so far not yet the main focus of the space photometry, yet those that were monitored revealed a much larger diversity in variable phenomena than anticipated. Coherent pressure and gravity modes, damped modes, rotational modulation, magnetic and wind variability, are among the ingredients detected in the space photometry of single and binary OB stars, while some of the binaries in addition revealed variations connected with tides. Asteroseismic modelling of OB stars requires physical ingredients that are quite different from those adopted for solar-like oscillations in slowly-rotating sun-like stars. We illustrate why rotation cannot be ignored in pulsation computations if the aim is to derive trustworthy asteroseismic inferences about the structure of massive stars. Moreover, we provide the most important aspects of the input physics of stellar models to focus upon in the forward modelling of pulsators born with a convective core and a radiative envelope, stressing critical assessment of the mode density as the stars evolve. While challenges occur for the interpretation of the observed variability of OB stars, opportunities to understand the transport of angular momentum and of chemicals in the radiatively stratified layers of massive stars are outstanding and of major importance. We show how asteroseismology of massive stars has the potential to improve stellar evolution models in the mass regime where they are most uncertain. We end the talk by highlighting the major asset of combined TESS, Gaia, and spectroscopic data interpretation for future asteroseismology of the most massive stars in the Milky Way and in the Magellanic Clouds. 84

87 Talks: Friday, 13th July Unravelling the mysteries of rotation and pulsation in main sequence A and F stars with the Kepler/K2 and TESS space missions. (Invited) D. M. Bowman 1 (1) Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001 Leuven, Belgium. Although it has been almost a decade since the launch of the Kepler Space Telescope, these high-quality photometric data continue to provide new and exciting insights of the interior physics of intermediate-mass main-sequence A and F stars. These stars exhibit a diverse range of behaviour, and provide us with the opportunity to probe rotation, pulsation, binarity, and magnetism in an interesting transition region between low- and high-mass stars within the Hertzsprung-Russell diagram. In the last year, significant advances in our understanding of main sequence A and F stars, which includes the gamma Doradus, delta Scuti, and roap stars, have been achieved by combining Kepler/K2 observations with state-of-theart theoretical models of stellar structure and evolution. In particular, detailed studies of interior rotation using high-order gravity modes in intermediate-mass stars have revealed that a quasi-uniform radial rotation profile appears to be ubiquitous irrespective of mass, age or rotational velocity. Therefore, intermediate-mass stars provide valuable constraints on angular momentum mechanisms within stellar interiors, with the exact physics responsible for this remaining an open question. Furthermore, since main-sequence A and F stars are progenitors of red giant stars, they also represent a unique opportunity for exploring angular momentum transport as a function of stellar evolution. In this talk, I will provide an overview of the recent significant discoveries and advances in our understanding of stellar physics that have been achieved using observations of mainsequence A and F stars from the Kepler and K2 space missions, with a particular focus on the synergy between rotation and pulsation. Moreover, I will discuss our expectations and the prospects of studying rotation, pulsation, binarity, and magnetism in a large sample of main sequence A and F stars with the TESS mission. 85

88 Talks: Friday, 13th July Constraining internal mixing of massive stars from gravity-mode oscillations, surface abundances, and Gaia astrometry M. G. Pedersen 1 C. Aerts 1,2, P. I. Pápics 1, T. M. Rogers 3,4 (1) Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, 3001, Leuven, Belgium. (2) Department of Astrophysics/IMAPP, Radboud University Nijmegen, 6500 GL, Nijmegen, The Netherlands. (3) Department of Mathematics & Statistics, Newcastle University, UK. (4) Planetary Science Institute, Tucson, AZ, 85721, USA. The treatment of convective core overshooting provides one of the largest uncertainties in stellar structure and evolution models of stars with convective cores. Stars with gravity-mode oscillations, which probe the deep stellar interior, provide the best opportunity to constrain core overshooting and any additional mixing in the near-core regions adopted in models. Gravity modes are highly sensitive to the amount of mass in the overshooting layer and to the chemical gradient left behind as the convective core retreats during the main-sequence evolution of massive stars. The effect of such chemical gradients are detected as deviations in the period spacings of gravity modes. Additional mixing processes just above the convective core change the shape of the chemical gradients and thereby directly impact the morphology of gravity-mode period spacings. In this talk we demonstrate the capabilities of gravity-mode oscillations detected in Kepler space photometry to constrain a) the shape of convective core overshooting, and b) radiative envelope mixing, when combined with spectroscopically derived surface abundances and astrometry from Gaia. We provide results from forward asteroseismic modelling of slowly pulsating B stars observed by the Kepler space telescope and discuss future prospects of such modelling efforts. 86

89 Talks: Friday, 13th July Mode classification in fast-rotating stars using a machine learning algorithm G. M. Mirouh 1 G. C. Angelou 2, D. R. Reese 3 (1) International School of Advanced Studies (SISSA), Trieste, Italy. (2) Max Planck Institute for Astrophysics (MPA), Garching bei Muenchen, Germany. (3) LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, Meudon, France. Delta Scuti stars are fast rotators whose spectra are very difficult to interpret. In particular, rotational effects scramble the oscillation spectrum so that we can no longer use simple spherical harmonics to characterize the modes. Theoretical work suggest that modes in fast-rotating stars can be split in various categories based on their geometry. While these categories cannot be readily identified in observations, recent work exploits hints of regularity (the so-called island modes). Their large separation scales with the mean density of the star, therefore paving the way to ensemble asteroseismology of delta Scuti stars. We compute the oscillation spectra of fully-consistent two-dimensional modes of fast-rotating stars, taking into account centrifugal distortion and Coriolis forces. We train a 2D convolutional neural network to classify automatically the modes in the theorized categories to bring out the expected patterns. In this talk, I will discuss the obtained regularities, how they correlate with stellar fundamental parameters, and the comparison with observed stars. 87

90 Talks: Friday, 13th July Characterisation of gravity and Rossby modes in hundreds of Kepler γ Doradus stars G. Li 1,2 T. R. Bedding 1,2, S. J. Murphy 1,2, T. Van Reeth 1,2, V. Antoci 1,2, R. Ouazzani 1,2 (1) Sydney Institute for Astronomy, School of Physics, University of Sydney, Australia. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. We present our analysis of 450 Kepler γ Doradus stars. These stars are pulsating mainly in gravity modes, but the periods are no longer equally-spaced due to core rotation and molecular weight gradients. So far we have discovered 600 period spacing patterns from 450 stars. These results constitute the largest γ Dor sample thus it is possible to reveal some new statistical relations. For dozens of slowly-rotating stars, we show how rotation distorts the asymptotic relation. In rapid rotators, we find that g-mode period spacings and their gradient (slope) are both positively correlated with period. Additionally, Rossby modes are seen in tens of stars. They have a negative correlation between the slope and mean period, which is twice the mean period of prograde gravity modes. These stars are very useful for understanding the physics of rotation and angular momentum transport in main sequence stars, and can place much needed constraints on diffusive mixing and chemical gradients, whilst also providing stellar ages. As this is the first sample with significant Rossby modes, we have the unprecedented opportunity to study these unfamiliar modes, like their instability strip, excitation mechanism and surface rotation. Period in d 88

91 Talks: Friday, 13th July Asteroseismology of solar-like stars with Kepler and K2 (Invited) S. Basu 1 (1) Department of Astronomy, Yale University, USA. Ground-based data had shown that asteroseismic analyses of stars other than the Sun is possible. However, it was not before space-based instruments began collecting asteroseismic data on a larger number of stars that the field really flourished. In this review I shall discuss some of the more interesting results that we have obtained thus far. I shall also discuss what we may expect to learn with data from TESS. 89

92 Talks: Friday, 13th July Explaining Deviations from the Scaling Relationship of the Large Frequency Separation Joel J. M. Ong 1 Sarbani Basu 1 (1) Department of Astronomy, Yale University, 52 Hillhouse Ave., New Haven, CT 06511, USA. Asteroseismic large frequency separations possess great diagnostic value. However, their expressions as scaling relations are predicated on homology arguments which may not hold in general, resulting in mass- and temperature-dependent deviations in consequence of stellar evolution, particularly on the red giant branch (White et al., 2011). Moreover, the firstorder asymptotic expressions, which should in principle account for this structural evolution, deviate more from fitted frequency-separation estimates than do the simple scaling relations, and exhibit qualitatively different behaviour. We discuss the lowest-order corrections to these asymptotic expressions, and show that the discrepancy can be accounted for by the evolution of the inner and outer acoustic turning points of the asteroseismic mode cavity, which is typically neglected in first-order asymptotic analysis. This permits us to use a single expression for the large frequency separations of both RGB and main-sequence stars, except at transition points between asymptotic regimes, where the WKB approach fails. The existence of such transition points provides theoretical justification for separately calibrated scaling relations for stars in different evolutionary stages νfit/ νest α(νmax) ν α ν M@ 0.9 M@ 1.0 M@ 1.1 M@ 1.2 M@ 1.3 M@ 1.4 M@ 1.5 M@ 1.6 M@ Teff/K

93 Talks: Friday, 13th July Asteroseismic modelling of solar-type stars: internal systematics from input physics and surface correction methods B. Nsamba 1,2 T. L. Campante 1,2, M. J. P. F. G. Monteiro 1,2, M. S. Cunha 1,2, B. M. Rendle 3,4, D. R. Reese 5, K. Verma 4 (1) Instituto de Astrofísica e Ciências do Espaço, Universidade do Porto, Rua das Estrelas, PT Porto, Portugal. (2) Departamento de Física e Astronomia, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre, s/n, PT Porto, Portugal. (3) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, UK. (4) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (5) LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, Meudon, France. Asteroseismic forward modelling techniques are being used to determine fundamental properties (e.g. mass, radius, and age) of solar-type stars. The need to take into account all possible sources of error is of paramount importance towards a robust determination of stellar properties. We present a study of 34 solar-type stars for which high signal-to-noise asteroseismic data is available from multi-year Kepler photometry. We explore the internal systematics on the stellar properties, that is, associated with the uncertainty in the input physics used to construct the stellar models. In particular, we explore the systematics arising from: (i) the inclusion of the diffusion of helium and heavy elements; and (ii) the uncertainty in solar metallicity mixture. We also assess the systematics arising from (iii) different surface correction methods used in optimisation/fitting procedures. The systematics arising from comparing results of models with and without diffusion are found to be 0.5%, 0.8%, 2.1%, and 16% in mean density, radius, mass, and age, respectively. The internal systematics in age are significantly larger than the statistical uncertainties. We find the internal systematics resulting from the uncertainty in solar metallicity mixture to be 0.7% in mean density, 0.5% in radius, 1.4% in mass, and 6.7% in age. The surface correction method by Sonoi and Ball s two-term correction produce the lowest internal systematics among the different correction methods, namely, 1%, 1%, 2%, and 8% in mean density, radius, mass, and age, respectively. Stellar masses obtained using the surface correction methods by Kjeldsen et al. and Ball & Gizon s one-term correction are systematically higher than those obtained using frequency ratios. 91

94 Talks: Friday, 13th July Studying mixing in the outer layers using the signatures of acoustic glitches from Kepler data K. Verma 1 V. Silva Aguirre 1 (1) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. It is well known that we need atomic diffusion to reproduce better the seismic structure of the Sun. It is also well known that the stellar models of mass approximately greater than 1.4M (depending on metallicity) predict complete depletion of helium and heavy elements in the envelope, in contrast to the classic measurements of spectroscopic elemental abundances and recent detections of the helium glitch signature in such stars. To reconcile the above, various physical processes have been proposed to counteract atomic diffusion, e.g., turbulent diffusion at the base of the deepest surface convection zone and mass loss in the envelope. In this talk, I shall demonstrate how the detected helium glitch signature can be used to constrain these processes. In particular, I shall take an example of turbulent diffusion as the counteracting process together with the radiative levitation to be fully consistent, and show that we need at least an order of magnitude more envelope mixed mass to prevent helium settling than what has been quoted in the literature from the measurements of heavy element abundances. 92

95 Talks: Friday, 13th July Testing stellar physics with asteroseismic inversions for the core-structures of solar-type stars E. P. Bellinger 1,2,3,4 S. Basu 2, S. Hekker 1,3 (1) Max Planck Institute for Solar System Research, Germany. (2) Department of Astronomy, Yale University, USA. (3) Stellar Astrophysics Centre, Aarhus University, Denmark. (4) Institute of Computer Science, University of Göttingen, Germany. We present measurements of internal sound speed throughout the cores of 20 solar-type stars from the Kepler LEGACY sample obtained via asteroseismic structure inversion. We compare the measured stellar structures with best-fitting evolutionary models constructed using a variety of physics inputs namely, with/without element diffusion, and with/without convective core overshooting. While in some cases we find good agreement between the inferred asteroseismic structures and the models, in other cases we find substantial differences. We furthermore find that none of these choices of physics inputs improve the situation for the discrepant stars. We speculate on potential causes of the discrepancies, and highlight the prospect of using these stars to constrain theories of stellar interiors. 93

96 Talks: Friday, 13th July The p-g diagram for oscillating subgiants with Kepler and TESS T. R. Bedding 1,2 M. Keen 1,2, Y. Li 3, T. Li 1,2,4, H. Kjeldsen 2 (1) School of Physics, University of Sydney 2006, Australia. (2) Stellar Astrophysics Centre, Aarhus University, Denmark. (3) Department of Astronomy, Beijing Normal University, Beijng , China. (4) Key Laboratory of Solar Activity, National Astronomical Observatories, Chinese Academy of Science, Beijing , China. Bumping of l = 1 modes in subgiant stars from their regular spacings arises because these modes are mixed. Each observed mode arises from coupling between a p-mode in the envelope and a g-mode in the core. It has long been recognised that mixed modes have great potential for asteroseismology because their frequencies are very sensitive to stellar interiors and because they change quite rapidly as the star evolves (e.g., Dziembowski and Pamyatnykh, 1991; Christensen-Dalsgaard et al., 1995). However, a direct comparison of observations with models involves adjusting the model parameters to fit the observed frequencies, which can be difficult, time-consuming and highly model-dependent. We have previously suggested that the information contained in the mixed modes can be used more elegantly. This is done by consider the frequencies of the avoided crossings themselves, which reveal the frequencies of the g modes in the core, as shown in panel (a) of the figure, which is one frame of a movie showing the evolution of a solar-mass star. Most of the diagnostic information contained in the mixed modes can be captured in this way. This leads us to a new asteroseismic diagram, inspired by the classical C-D diagram, in which the frequencies of the avoided crossings are plotted against the large separation of the p modes. This p-g diagram, so named because it plots g-mode frequencies versus p-mode frequencies, is a very instructive way to display results of many stars and to make a comparison with theoretical models. We have fitted to the avoided crossings and used this to calculate tracks in the p-g diagram for a range of masses and metallicities (panel b). And for the first time, we can populate this p-g diagram with dozens of subgiants that were observed by Kepler, as shown in panel (c). Importantly, most of these stars were only observed for one quarter or less, and they have been neglected until now. The p-g diagram gives us a quick and robust way to determine masses and ages for subgiants. This will have great application to TESS, which will observe very large numbers of subgiants across the whole sky. We suggest that subgiants will have an important role in the galactic archaeology that is done with TESS, as a nearby population to complement to the more distant red giants. 94

97 Talks: Friday, 13th July Core rotation braking on the red giant branch: characterizing the influence of the mass on the braking efficiency C. Gehan 1 B. Mosser 1, E. Michel 1 (1) LESIA, PSL, Observatoire de Paris, Université Pierre et Marie Curie, Université Denis Diderot, CNRS. Red giants are asteroseismic targets of high interest as we have a direct view on the physical conditions in their core through mixed modes, which is not the case for solar-type pulsators on the main sequence. However, we still need to identify the physical mechanisms that transport angular momentum inside red giants, leading to the slow-down observed for the red giant core rotation. Hence, large-scale measurements of the red giant core rotation are of prime importance to obtain tighter constraints on the efficiency of the internal angular momentum transport, and to study how this efficiency changes with stellar parameters such as the mass. The latest measurements for almost 900 red giant branch stars highlight that the core rotation is almost constant along the red giant branch, with values largely independent of the mass (Gehan et al. 2018). The effort is now focused on the interpretation of these results based on stellar modeling. Combining rotational kernels with stellar inertia profiles for different stellar masses corresponding to different evolutionary stages on the red giant branch, we seek at characterizing how the efficiency of the angular momentum transport varies along the red giant branch and how it depends on the stellar mass. I will present the main conclusions of the study of Gehan et al as well as constraints on the efficiency of the angular momentum transport brought by models. 95

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101 Posters: Galactic archaeology 10 99

102 Posters: Galactic archaeology P18: Utilising the K2 observations to validate RR Lyrae variables from large sky surveys Á. L. Juhász 1,2 L. Molnár 1, E. Plachy 1, L. Rimoldini 3 (1) Konkoly Observatory, MTA CSFK, H-1121, Budapest, Konkoly Thege Miklós út , Hungary. (2) Department of Astronomy, Eötvös Loránd University, H-1117, Budapest, Pázmány Péter sétány 1/a, Hungary. (3) Department of Astronomy, University of Geneva, Chemin d Ecogia 16, CH-1290, Versoix, Switzerland. The Kepler space telescope obtained a large collection of continuous RR Lyrae light curves. These can be used to validate classifications coming from large-scale surveys such as the Pan- STARRS PS1 3pi survey and Gaia DR2, aiming at mapping the structure of the Milky Way. We cross-matched these catalogs with the targets observed during the Kepler K2 mission to validate their classifications. This way we are able to provide independent assessments of the purity and completeness of the surveys, verify new discoveries and identify false positives. We found that in the case of PS1, the purity strongly depends on the galactic latitude, with many eclipsing binaries found in the fields-of-view targeting the Galactic anticenter. In the case of the Gaia classifications, we found the success rate of the various subtypes of RR Lyrae stars to be very different. 100

103 Posters: Stellar physics

104 Posters: Stellar physics P01: K2 observations of 33 Lib D. L. Holdsworth 1,2 H. Shibahashi 3, M. S. Cunha 4, D. W. Kurtz 1, D. M. Bowman 5 (1) Jeremiah Horrocks Institute, University of Central Lancashire, Preston PR1 2HE, UK. (2) Department of Physics, North-West University, Mafikeng Campus, Private Bag X2046, Mmabatho 2745, South Africa. (3) Department of Astronomy, The University of Tokyo, Tokyo , Japan. (4) Centro de Astrofísca e Faculdade de Ciências, Universidade do Porto, Rua das Estrelas, P Porto, Portugal. (5) Instituut voor Sterrenkunde, KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium. We present the analysis of K2 data of the well known roap star 33 Librae (HD ). We have identified new pulsation modes in this star and provide a new value for the large frequency separation. We show that the frequency separations around the dominant mode are replicated around its harmonic implying that there are non-linear interactions between this mode and the other lower amplitude modes. This is a new observational phenomenon that has not previously been observed in other roap stars. The K2 data are consistent with a rotation period much larger than 80 days, and show up to four harmonics of the dominant mode, reaffirming the highly non-sinusoidal pulsations seen in the roap stars. 102

105 Posters: Stellar physics P02: Solar-like oscillators in eclipsing binaries P. Gaulme 1,3 M. Benbakoura 2, R. A. Garcia 2, J. Jackiewicz 3, P. Beck 4, J. McKeever 5, S. Mathur 4 (1) Max Planck Institut für Sonnensystemforschung. (2) CEA/IRFU (Institut de Recherche sur les lois Fondamentales). (3) New Mexico State University. (4) Instituto de Astrofísica de Canarias. (5) Yale University. For the past five years, a few tens of solar-like oscillators have been identified in eclipsing binaries, from the Kepler data. All of them are red giants so far. On one hand, these systems are precious because they allow for testing the reliability of asteroseismology by providing stellar masses and radii independently from seismology. On the other hand, they offer unique views on the evolution of binary systems thanks to the information carried by their oscillations modes. The purpose of this presentation is to first make the point about testing the asteroseismic scaling laws, thanks to the results of Frandsen+2013, Rawls+2016, Gaulme+2016 and Brogaard+2018, as well as a new sample of red giants in eclipsing biaries identified by Benbakoura et al (in prep.). Secondly, we also present new results about oscillation properties and evolution of binary systems (Beck+ 2018). We conclude about the prospects we expect from both GAIA and TESS. 103

106 Posters: Stellar physics P03: Asteroseismic analysis and spectrophotometric study of KIC , a Kepler red giant binary with active mass transfer A. Bódi 1,2 L. L. Kiss 1,3, T. Mitnyan 2 (1) Konkoly Observatory of the Hungarian Academy of Sciences, Hungary. (2) Department of Experimental Physics, University of Szeged, Hungary. (3) Institute of Astronomy, School of Physics, University of Sydney, Australia. Ellipsoidal binary stars are evolved systems in which one of the components is a red giant star which tidally distorted surface results in sinusoidal light curve shape with two minima of different depths. These kind of objects form Sequence E of the ellipsoidal red giants in the Magellanic Clouds. We present the detailed analysis of KIC , a red giantred giant binary orbiting in a long-period orbit of 118 days, which spectroscopic follow-up observations started in mid The light- and radial velocity curve modeling results in a low-mass binary which is currently undergoing a mass-transfer phase, without any sign of it in the IR-bands. The calculated luminosity distance is consistent with the value derived from the Gaia DR2 parallax. The Fourier-spectrum of the residual light curve shows a very rich frequency content which can be connected to the primary component. Comparing the pulsation pattern to similar single red giants, some oscillation modes can be identified, but the physical origin of several modes remains unknown. Using the scaling relations, asteroseismic mass and radius can be calculated, which yields higher values than the dynamical ones. The granulation properties of the primary component are in agreement with the expected ones of model calculations. 104

107 Posters: Stellar physics P05: Determination of surface rotation of Kepler solar-type stars A. R. G. Santos 1 R. A. Garcia 2, S. Mathur 3, G. V. Simonian 4, M. H. Pinsonneault 4, J. van Saders 5 (1) Space Science Institute, Colorado, USA. (2) IRFU, CEA, Université Paris-Saclay, France. (3) Instituto de Astrofísica de Canarias, Tenerife, Spain. (4) Department of Astronomy, The Ohio State University, Ohio, USA. (5) Carnegie Observatories, California, USA. Periodic modulations of stellar light curves may result from dark spots crossing the visible stellar disc. By studying spot-induced modulations, it is possible to learn about stellar surface rotation and magnetic activity. In this work, we analyze Kepler long-cadence data for a large sample of ( 50000) solar-type stars (T eff < 5500 K and log g > 3.5), determining surface rotation periods for those with measurable spot modulation of the light curves. We use KADACS (Kepler Asteroseismic Data Analysis and Calibration Software; García et al. 2011) light curves obtained with three different filters (20-d, 55-d, and 80-d filters) and, for comparison, PDC-MAP (Presearch Data Conditioning - Maximum A Posteriori; e.g. Jenkins et al. 2010) light curves. The average surface rotation is obtained through the implementation of the methodology developed by García et al. (2014), which combines a time-frequency analysis based on wavelets and the auto-correlation function (e.g. McQuillan et al. 2014). Reliable rotation periods are finally determined by comparing the results for the three KADACS data sets and by comparing those with the results for the PDC-MAP light curves. We also take special care to identify possible classical pulsators and red giants which are polluting the target sample of solar-type stars. 105

108 Posters: Stellar physics P06: Interpretation of the Kepler data of the rapidly rotating B-type pulsators KIC W. Szewczuk 1 J. Daszyńska-Daszkiewicz 1 (1) Astronomical Institute of the Wrocław University, Kopernika 11, PL Wrocław, Poland. KIC is the rapidly rotating (V sin i = 242 ± 14 km s 1 ) star of B5 IV-Ve spectral type. The asymptotic pattern for g modes in its Kepler oscillation spectrum was identified by Papics et al (2017). We perform seismic modelling of this pulsator using MESA code and employing the traditional approximation. Our main goal was to find constraints on the amount of mixing in the deep interior of the star. Unusually, the quality of the fit appears hardly sensitive to the amount of overshooting from the convective core. Various rotational mixing processes are tested, to explain this result. In particular, the effects of the Eddington-Sweet circulation and the Goldreich-Schubert-Fricke instability are investigated. Moreover, we check the instability of pulsational modes corresponding to the observed frequencies. It turns out that KIC is one more B-type pulsator for which a significant increase of the standard opacities is necessary. 106

109 Posters: Stellar physics P07: Automated asteroseismic peak detections A. García Saravia Ortiz de Montellano 1,2 S. Hekker 1,2, N. Themeßl 1,2 (1) Max-Planck-Institut fur Sonnensystemforschung, Göttingen, Germany. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. Detailed asteroseismic analyses of the data provided by the Kepler space observatory have the potential to revolutionize our understanding of stars. However, such detailed analyses, known as peak bagging, have so far been obtained for only a small percentage of the observed stars. One of the major challenges in peak bagging, specially in red giant stars, is identifying how many solar-like oscillation modes are visible in a power density spectrum. Identification of oscillation modes is usually done by visual inspection. This approach is time-consuming and has a degree of subjectivity. Here, we present a peak-detection algorithm especially suited for the detection of solar-like oscillations. It reliably characterizes the solar-like oscillations in a power density spectrum and estimates their observed parameters without human intervention. Furthermore, we provide metrics that characterize the false positive and false negative rates. These metrics provide further information about the reliability of a detected oscillation mode or the significance of a non-detection. The algorithm presented here opens the possibility for detailed and automated peak bagging of the thousands of solar-like oscillators observed by Kepler. 107

110 Posters: Stellar physics P08: Spectroscopic confirmation of the binary nature of the hybrid pulsator KIC A. Derekas 1,2 G. Dálya 3, R. Szabó 2, T. Borkovits 4,2, H. Lehmann 5, K. Kinemuchi 6, J. Southworth 7, B. Csák 2,1, J. Kovács 1, Gy. M. Szabó 1,2, Sz. Mészáros 1,8 (1) ELTE E` otv os Loránd University, Gothard Astrophysical Observatory, Szombathely, Hungary. (2) Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, H-1121 Budapest, Konkoly Thege Miklós út 15-17, Hungary. (3) Institute of Physics, E` otv os University, 1117 Budapest, Hungary. (4) Baja Astronomical Observatory of Szeged University, H-6500 Baja, Szegedi út, Kt. 766, Hungary. (5) Thüringer Landessternwarte Tautenburg, Karl-Schwarzschild-Observatorium, Tautenburg, Germany. (6) Apache Point Observatory, Sunspot NM 88349, USA. (7) Astrophysics Group, Keele University Newcastle-under-Lyme, ST5 5BG, UK. (8) Premium Postdoctoral Fellow of the Hungarian Academy of Sciences. We present the analysis of the hybrid γ Doradus -δ Scuti pulsator KIC We used Kepler space telescope photometry, applied the frequency modulation (FM) method and found that KIC was a good candidate being in binary system. We determined the orbital period as 95 days and the orbit is slightly eccentric. In order to prove these, we took spectroscopic measurements which revealed KIC is a double lined binary and the fit of the radial velocity curve is in a good agreement with the results of the FM method. 108

111 Posters: Stellar physics P09: Focusing our asteroseismic vision: The surface effect from convection simulations R. Trampedach 1,2 G. Houdek 1, R. Collet 1, J. Christensen-Dalsgaard 1 (1) Stellar Astrophysics Centre, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (2) Space Science Institute, 4750 Walnut Street, Boulder, CO 80301, U.S.A. The asteroseismic surface effect limits our ability to reach the full potential of Kepler, and soon TESS observations. This systematic frequency shift between observed modes and theoretical predictions, gives misleading model-matches to observations, and leads to correlations with other stellar parameters. When matching models to observations, it is not unusual to have several islands in parameter-space of equally good matches and little guidance as to which, if any, is the actual parameter-set for the star. These islands are often further apart than observational uncertainties would suggest, and can correspond to different evolutionary stages. Accurate modelling of the physics giving rise to the surface effect is crucial for getting better and more reliable matches of models to observations. We have been extracting the various parts of the asteroseismic surface effect from a grid of 3D simulations of deep convective atmospheres. The structural part, an atmospheric expansion by convection, improves the surface stratification of stellar structure and evolution models. The modal part accounts for the direct interactions between convection and modes, and adds a term to the oscillation equations. I will give an update on the project. 109

112 Posters: Stellar physics P10: Empirical relations for the estimation of stellar masses and radii A. Moya 1 F. Zuccarino 2, W. J. Chaplin 1, G. R. Davies 1 (1) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. (2) Universidad Internacional de Valencia (VIU), E Valencia, Spain. Empirical relations connecting different stellar characteristics are used in many astrophysical fields such as exoplanet characterization, stellar clusters, binary systems, gravitational microlensing, stellar dating, etc. Thanks to the precise stellar characterization provided by detached eclipsing binaries, asteroseismology and/or interferometry, we have been able to carry out a revision of empirical relations for the estimation of the stellar mass and radius. Gaia s data releases are also an opportunity for these relations since we will have, for the first time, accurate luminosities for millions of isolated stars. We present a total of 52 new or revised relations, those with an accuracy and precision better than 10% for almost all the cases. They cover almost all the possible combinations of observables. These relations aim to condense the information provided by detached eclipsing binaries, asteroseismology and/or interferometry into simple linear relations to estimate stellar masses and radii when these methods are not available. Finally, we have obtained a Random Forest model providing the best accuracies possible. 110

113 Posters: Stellar physics P12: Local Projective Noise Reduction Techniques for TESS Data P. C. Stine 1 N. Jevtic 1 (1) Department of Physics and Engineering, Bloomsburg University of Pennsylvania, USA. Local projective noise reduction techniques have been successful in reducing noise in power spectra, especially when a strong fundamental and harmonics are apparent at lower frequencies. Success has been achieved in efficiently reducing high frequency noise from one-month Kepler Space Telescope light curves. Applying the same methods to data from the Transiting Exoplanet Survey Satellite (TESS) presents challenges in that TESS will have shorter light curves (27 day) in many cases, larger pixels, which can lead to more crowding, and a deeper pixel depth which can cause cosmic rays to impact multiple pixels. In this poster, we examine the efficacy of local projective noise reduction methods on simulated TESS data. 111

114 Posters: Stellar physics P13: Direct Deconvolution: a method to minimize the effects of the observational window on power spectra M. Lares Martiz 1 R. Garrido 1, J. Pascual Granado 1 (1) Stellar Physics Department. Institute of Astrophysics of Andalusia. Spain. Fourier transforms of observed light curves, obtained by ground observations or by space photometers, exhibit interference effects that are consequence of the convolution of the true Fourier transform with a spectral window (Deeming, 1974). These interference effects make very difficult to identify non-radial oscillation modes of multiperiodic variable stars, i.e. an asteroseismic analysis. This identification is usually made by heuristic methods such as the detection of periodicities or frequency patterns that match the large splitting or small splitting as used in the sun itself and solar-type stars. But these frequency patterns are not easily observed in the light curves of δ scuti stars or other types of variables since Tassoul asymptotic theory is only valid for solar-type stars. In order to identify potential patterns, it is necessary to obtain a reliable list of frequencies that are normal modes of the star excluding those originated by spurious peaks in the power spectra. For the moment, the reliable list has been obtained using algorithms such as Period04 or SigSpec that performs a prewhitening of the light curve in the same manner as the CLEAN algorithm (Roberts, 1986) do for radio observation. But in our case this is not a solution because the frequencies found must have a physical meaning and not be just a way to recover a CLEANed radio image. The Direct Deconvolution (DD) method is aimed to fulfill the purpose of removal or minimizing the interference in power spectra due to the observational window. Its theoretical fundamentals are explained in this poster, as well as some issues to be addressed before the full implementation of the method regarding numerical problems that arise when testing the algorithm. Here we show preliminary results on the application of the DD method to numerical simulations and a δ Scuti star observed by Kepler. 112

115 Posters: Stellar physics P14: Systematical Differences in Spectroscopic Analysis D. Slumstrup 1 F. Grundahl 1, V. Silva Aguirre 1, K. Brogaard 1 (1) Stellar Astrophysics Centre, Aarhus University, Denmark. Many different methods and programs are available for a spectroscopic analysis of optical stellar spectra. It is well known that the different options do not always yield the same result, however the extent of the differences between programs can be very significant in some cases. We have gathered high signal-to-noise and high resolution data for three red clump stars with similar parameters and all observed with the same instrumental setup to homogenize the analysis. We chose to do a line-by-line analysis, measuring equivalent widths and comparing them to stellar atmospheric models to determine atmospheric parameters by invoking excitation and ionization equilibrium. We have tested different line lists, differences in laboratory and astrophysical oscillator strengths, and different programs to measure equivalent widths. The Figure shows the results for different combinations of these. The resulting atmospheric parameters vary by up to 200 K in effective temperature and 0.5 dex in log g, which is much more than anticipated. In order to choose between the different line lists and equivalent width measurements, we have used results from binary stars and asteroseismology to constrain the surface gravity, which allows us to discard some line lists and programs. With this poster, we will present the results of this analysis. TAME + C14 ARES + C14 Daospec + T13 Daospec + F10 Daospec + Golden Daospec + B01 Daospec + C14 lab Daospec + C T eff [K] log g [dex] [Fe/H] [dex] 113

116 Posters: Stellar physics P15: Solar-like oscillations in subgiants: mixed mode parameters Yaguang Li 1,2 Timothy R. Bedding 2,3, Tanda Li 2,3, Shaolan Bi 1 (1) Department of Astronomy, Beijing Normal University, Beijing , China. (2) Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia. (3) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. We analyze oscillation mode parameters of early subgiants observed by 4 year Kepler mission. We estimated mode amplitudes, line widths, and frequencies using a power spectrum model with rotational splittings and fitted them in the Bayesian framework with MCMC. The three parameters are set to vary for modes with different radial node and angular degree. Using the results, we then investigate properties of mixed modes for 12 stars. We examined two methods constraining coupling strength and g mode period spacing, one using mixed mode frequency (Unno et al. 1989) and another using mode inertia (Shibahashi 1979) calculated with amplitudes and line widths according to Benomar et al. (2014). We found the latter is easily fitted to non-physical results because the mode inertia is more uncertain. Furthermore, our results were used to estimate stellar parameters through modelling (Li et al. and Bedding et al., this conference). Our sample includes 11 stars with observation duration shorter than 120 days. These stars exhibit high enough S/N to show clear mixed mode oscillation structure, indicating a promising application potential for TESS M/M ( Hz) T eff (K)

117 Posters: Stellar physics (1) LESIA, Observatoire de Paris. P16: The seismic performance B. Mosser 1 Question: I would like to observe this star, this bunch of stars, this stellar field, that open cluster.... with TESS or Plato. Is it possible to imagine the expected seismic result?... and, please, no complicated computations... no complicated calibration... and quantitative answers about the precision we can get would not hurt. Answer: The seismic simulator is the tool you need. Calibrated with CoRoT and Kepler data, it provides you in a model-independent way with the detectability of the oscillations and with the expected relative precision on, for instance, the stellar mass. 115

118 Posters: Stellar physics P19: Forward seismic modelling of the pulsating magnetic B-type star HD43317 B. Buysschaert 1,2 C. Aerts 1, D. M. Bowman 1, C. Neiner 2 (1) Institute of Astronomy, KU Leuven, Leuven, Belgium. (2) LESIA, Observatoire de Paris, Meudon, France. Large-scale magnetic fields are detected at the surface of about 10% of early-type (O, B, A) stars. These magnetic fields are stable over a long time scale (due to their fossil nature), have a simple geometry (often an oblique dipole), and have a strength of several 100G up to a few 10kG. Moreover, the results of theoretical calculations and numerical simulations show that these large-scale magnetic fields exist throughout the complete radiative layer where they may alter the structure. Specifically, these fields are anticipated to enforce uniform rotation and may suppress the extent of the convective-core overshooting layer. So far, the latter has been observationally demonstrated from pressure-mode oscillations for only one star, namely the slowly-rotating β-cep pulsator V2052 Oph, using forward seismic modelling. Inspired by this pioneering work, we selected the magnetic pulsator HD43317 for forward seismic modelling to determine its internal structure. This star is a moderate rotator, hosts a wellcharacterized dipolar magnetic field of 1.3 ± 0.3kG and, most importantly, its CoRoT light curve shows a rich frequency spectrum of many gravity mode frequencies that are sensitive to the near-core region. Here, we report on the successful seismic modelling of HD43317 using GYRE model frequencies in the Traditional Approximation, based on MESA stellar structure models. We deduce the stellar mass, age, and core overshooting. We also compare the effects of the Coriolis force and of the Lorentz force on the oscillations. Our results makes HD43317 the only magnetic g-mode pulsator with successful forward asteroseismic modelling to date. 116

119 Posters: Stellar physics P20: The coefficient of variation method: rapid, robust, precise, and fully automated detections of the ν max of solar-like oscillations K. J. Bell 1,2 S. Hekker 1,2, J. S. Kuszlewicz 1,2 (1) Max Planck Institute for Solar System Research, Göttingen, Germany. (2) Stellar Astrophysics Centre, Aarhus, Denmark. We introduce a new, fully automated method for detecting the frequency of maximum solarlike oscillation power, ν max, from time series photometry. The coefficient of variation (CV) spectrum is a statistical representation of the data the ratio of the standard deviation to the mean calculated for bins in the power spectrum that sensitively reveals solar-like oscillations in the presence of granulation. By mimicking the approach of an expert s visual inspection, our method yields precise ν max measurements (2.6% average error) and robust power excess detections (99% agreement with more involved methods) without fitting models to the colored-noise background. The CV method promises to accelerate the identification and asteroseismic analyses of solar-like oscillators in large data sets like Kepler, K2, and TESS. We demonstrate the success of our method in characterizing the APOKASC sample of oscillating red giants observed by Kepler. We also show how CV spectra can highlight targets of particular scientific value that exhibit astrophysical signals in addition to solar-like oscillations. 117

120 Posters: Stellar physics P22: Classifying the evolutionary state of Kepler red giants in the time domain. J. S. Kuszlewicz 1,2 S. Hekker 1,2, K. J. Bell 1,2, N. Themeßl 1,2, A. Garcìa Saravia Ortiz de Montellano 1,2 (1) Max-Planck-Institut für Sonnensystemforschung, Germany. (2) Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Denmark. The coming eras of TESS and PLATO will provide new challenges for evolutionary state classification of red-giant stars given the large number of stars being observed and the short datasets. We propose a new method based upon a supervised classification scheme that uses only summary statistics of the timeseries to predict the evolutionary state. Applying this to red giants in the APOKASC catalogue, we obtain a classification accuracy of 85% for the full 4 years of Kepler data. The method also generalises to shorter Kepler datasets, mimicking CoRoT, K2 and TESS achieving an accuracy greater than 81% even for the 27 day time series. This work helps to pave the way towards fast, reliable classification of vast amounts of data with a few, well-engineered features. 118

121 Posters: Stellar physics P23: First inferences on HD using asteroseismic data from the Hertzsprung telescope O. Creevey 1 F. Thevenin 1, F. Grundahl 2, P. L. Palle 3, E. Corsaro 4, D. Salabert 5, L. Bigot 1, R. Collet 2, V. Antoci 2, M. F. Andersen 2 (1) OCA, Nice, France. (2) Aarhus University, Denmark. (3) IAC, Tenerife, Spain. (4) Catania Obs, Italy. (5) CEA Saclay, France. In the era of large galactic and extra galactic surveys it is easy to forget that there are many nearby astrophysical laboratories that can also be used to provide important constraints on our knowledge of the Galaxy, as well as providing crucial insights on astrophysical processes inside stars and their atmospheres. In fact by addressing issues relevant to stellar physics, we can provide much better tools to the community for studying more distant populations. We present the case of HD , an old metal-poor (Population II) giant at a mere distance of 250 pc. Because it is metal-poor such a star provides an excellent laboratory for constraining models of stellar atmospheres and interiors of old stars. It is also a benchmark star for testing methodologies for interpreting millions of stars from the Gaia mission. In this poster we present the very first observations of sun-like oscillations in a metal-poor giant star using data from the SONG network. We detect global seismic quantites, and use these to infer properties of the star, in disagreement with previous claims. New data from the Gaia mission supports our asteroseismic results. 119

122 Posters: Stellar physics P25: The period-luminosity relation for δ Scuti stars using Gaia DR2 parallaxes E. Ziaali 1,2 T. R. Bedding 2,3, S. J. Murphy 2,3, T. Van Reeth 2,3 (1) Research Institute for Astronomy and Astrophysics of Maragha, Maragha, East Azerbaijan, Iran. (2) Sydney Institute for Astronomy, School of Physics, University of Sydney 2006, Australia. (3) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. We have constructed the period-luminosity relation for 286 δ Scuti stars from the catalogue of Rodriguez et al. (2000) by using the Gaia DR2 parallaxes. We plotted absolute V magnitudes against log P and we can distinguish two ridges, with a period ratio near 2. The ridge with longer periods is in agreement with the relation McNamara (2011) fitted to a number of metal-rich δ Scuti stars using the Hipparcos parallaxes, and presumably corresponds to the fundamental radial mode. We used Gaia DR2 parallaxes and Tycho V magnitudes for the period-luminosity relation of 2299 δ Scutis in the Kepler field. These show a similar distribution, also with two ridges. We discuss the possible explanations. 120

123 Posters: Stellar physics P26: Dynamical effects in type II Cepheids R. Smolec 1 P. Moskalik 1, E. Plachy 2, I. Soszynski 3 (1) Nicolaus Copernicus Astronomical Center, Warsaw, Poland. (2) Konkoly Observatory, MTA CSFK, Budapest, Hungary. (3) Warsaw University Observatory, Warsaw, Poland. We have analysed the photometry of 924 type II Cepheids from the Galactic bulge observed by the Optical Gravitational Lensing Experiment. We present several dynamical effects that we have detected in the sample including: (i) first examples of radial double-mode pulsation in BL Her-type stars, (ii) period doubled pulsation in three BL Her-type stars; (iii) perioddoubled pulsation in several W Vir stars with periods in between 15 and 20 d; (iv) period-4 pulsation in RV Tau-type star; (v) quasi-periodic modulation of pulsation in all sub-classes of type-ii Cepheids: BL Her, W Vir and RV Tau type stars. Most of these phenomena are reported in type II Cepheids for the first time. 121

124 Posters: Stellar physics P27: A nonlinear look at TESS simulated data N. Jevtic 1 P. Stine 1 (1) Department of Physics and Engineering, Bloomsburg University of Pennsylvania, USA. The high quality Kepler Space Telescope light curves have allowed us to develop applications of nonlinear time series analysis to the point that not only can we reduce noise efficiently, we can recoup time information by determining whether the sampling time is short enough to capture all the complexity at the source of a signal and by estimating time scales changing the delay. Moreover, we can preview power spectra, interpolate short gaps using a phase-space surrogates and, of particular interest for TESS data, validate cosmic ray signal rejection. Since simulated data represent the epitome of pre-processing, the available TESS simulated data may be useful in exploring one of the tenets of nonlinear time series analysis, that pre-processed data do not lend themselves to these tools. 122

125 Posters: Stellar physics P28: Type II and anomalous Cepheids in the K2 mission E. Plachy 1 M. I. Jurkovic 1,2, L. Molnar 1 (1) Konkoly Observatory, Research Centre for Astronomy and Earth Sciences, Hungarian Academy of Sciences, Budapest, Hungary. (2) Astronomical Observatory of Belgrade, Belgrade, Serbia. We present the analysis of Type II and anomalous Cepheid stars observed in Campaigns 4, 7, 12 and 13 of the K2 mission. We revised the classification of the short period stars (1-3 day) based on the Fourier parameters of the K2 light curves and examined the short cadence data of three anomalous Cepheids. Among the five longer period, W Virginis type stars, one shows alternation in the pulsation amplitudes indicating the presence of period doubling. This phenomenon was recently found to be common in the day period range of Type II Cepheids. 123

126 Posters: Stellar physics P29: Theoretical analysis of the evolution of the asymptotic parameters of the dipolar mixed modes of red giant stars M. Takata 1 (1) Department of Astronomy, School of Science, University of Tokyo, Japan. The dipolar mixed modes play a crucial role in asteroseismology of red giant stars since they propagate in not only the envelope but also the core, and hence provide the information about the internal structure throughout the entire stars. Because of the short wavelength of the constituent waves, the frequency spectrum of the modes are well described by the asymptotic theory. The parameters that characterise the spectrum include the large frequency separation, the period spacing, the coupling factor between the core and envelope oscillations, and the gravity offset. In this study, the variation of these parameters along with the evolution of the stars is examined by developing the theoretical expressions and applying them to the realistic stellar models. Comparison of the results of the present analysis with the observed frequency spectrum would be useful to quantify the accuracy of our understanding of the structure of the red giant stars. 124

127 Posters: Stellar physics P30: Proper treatment of convective boundaries in stellar evolution codes and their impact on the oscillation spectra of blue supergiants. A. Thoul 1 R. H. D. Townsend 2 (1) Space sciences, Technologies and Astrophysics Research (STAR) Institute, Université de Liège, Belgium. (2) University of Wisconsin-Madison, Madison, USA. Pulsating modes have been observed in blue supergiants, and explained in previous studies as non-radial pulsations excited by the kappa mechanism. This is surprising since those stars have dense radiative cores and a very large Brunt-Vaissala frequency, which produces an important damping of those pulsations when they enter the core. It has been suggested that an intermediate convection zone can prevent those modes from entering the core, and therefore prevent their damping. According to a previous study, several mechanisms such as mass loss, overshooting, and the treatment of the convective boundaries and the semiconvective regions, can strongly influence those ICZs, and therefore the ability of the blue supergiants to pulsate with g-modes. In addition, recent asteroseismic studies of SPB stars have also shown the importance of correctly modeling the convective core boundary. TESS should find hundreds of new beta Cephei stars, both on the main sequence and in the post-ms extension (blue supergiants), and thousands of new SPB stars. It is therefore very important to properly model the convective boundaries in stellar evolution codes to correctly interpret the observations obtained with TESS. We will describe the latest improved capabilities of the stellar evolution code MESA to properly model convective boundaries, and using the stellar oscillation code GYRE, we will show their impact on the oscillation spectra of blue supergiants. 125

128 Posters: Stellar physics P31: Spectroscopic Pulsational Analysis of Southern γ Doradus Stars E. Brunsden 1,2 K. R. Pollard 2, D. J. Wright 3, P. De Cat 4, P. L. Cottrell 5 (1) Department of Physics, University of York, York, UK. (2) Department of Physics and Astronomy, University of Canterbury, Christchurch, New Zealand. (3) Department of Astrophysics, University of New South Wales, Sydney, Australia. (4) Royal Observatory of Belgium, Brussels, Belgium. (5) Monash Centre for Astrophysics, School of Physics and Astronomy, Monash University, Victoria 3800, Australia. The g-mode pulsations in γ Doradus stars are identified using high-resolution spectroscopy to monitor changes in the line profiles. For more than 50 southern candidates and bona fide class members time-series line profiles are analysed and pulsational frequencies and modes are compared. Binary stars and non-pulsators are identified. Most of the stars are TESS short-cadence targets offering a valuable comparison and extension of understanding of the physics of these non-radial pulsators. 126

129 Posters: Stellar physics P32: Are Stellar Inclination Angles Distributed Randomly? J. S. Kuszlewicz 1,3 W. J. Chaplin 2,3, K. J. Bell 1,3, T. S. H. North 2,3, S. Hekker 1,3 (1) Max-Planck-Institut für Sonnensystemforschung. (2) University of Birmingham. (3) Stellar Astrophysics Centre (SAC). The stellar inclination angle - the angle between the rotation axis of a star and our line of sight - is a useful quantity in many analyses. The angle itself and the distribution of angles in an ensemble can help in many different areas; from the characterisation of exoplanetary and eclipsing binary systems, to formation processes in clusters. We propose a method based on asteroseismology and a Bayesian hierarchical scheme for both extracting the inclination angle of a single star, and inferring the inclination angle distribution of an ensemble of stars. We successfully applied this technique to artificial datasets with 2 different known underlying inclination angle distributions to verify the method. We also show, by applying this technique to 121 red giant stars observed with Kepler, that the distribution of this real ensemble is consistent with a random distribution of angles. This paves the way towards analyses on larger ensembles stars as well as providing a method to accurately and robustly extract inclination angles from red giant stars. 127

130 Posters: Stellar physics P33: Correlation between the non detection of acoustic modes in solar-like stars and their magnetic activity S. Mathur 1,2 R. A. Garcia 3, L. Bugnet 3, P. G. Beck 1,2, N. Santiago 4, A. Santos 5 (1) Instituto de Astrofisica de Canarias, La Laguna, Tenerife, Spain. (2) Departamento de Astrofisica, Universidad de La Laguna, Tenerife, Spain. (3) IRFU, CEA, Universite Paris-Saclay, Gif-sur-Yvette, France. (4) University of Puerto Rico, Cayey, Puerto Rico. (5) Space Science Institute, Boulder, CO, USA. During the first ten months of the Kepler mission, over 2000 stars were observed for one month in short cadence mode allowing us to look for stochastically excited acoustic modes. This led to the detection of solar-like oscillations in only about 540 stars (Chaplin et al. 2011a). Chaplin et al. (2011b) explained the lack of detection in most of the other stars as a consequence of their high surface magnetic activity. However the sample of stars studied was polluted with many classical pulsators and red giants. Here, we re-visit the study on a cleaner sample of stars where we have removed stars with newly detected oscillations using the latest DR25 from Kepler along with the classical pulsators and red giants that were polluting the sample. For the remaining main-sequence solar-like stars, we measured the rotation and magnetic activity proxy based on photometric data (called Sph, Mathur et al. 2014). While close to half of this sample has an Sph value larger than the one of the Sun, we find that a large fraction of stars without oscillations detected have a low magnetic activity level, which was unexpected. We also investigate on the origin of these missing detections using new spectroscopic observations of those stars (in particular in terms of metallicity and chromospheric activity). An upper limit of Sph is also inferred as a limit above which no pulsations were detected. Understanding the non detection of solar-like oscillations is key to predict the yield of solar-like pulsating stars for missions such as TESS and PLATO where the detection of solar-like oscillations will allow us to better characterize the stars, in particular the ones hosting planets. 128

131 Posters: Stellar physics P34: Period spacings in red giants: toward a complete description of the mixed-mode pattern (1) LESIA, Observatoire de Paris. B. Mosser 1 Oscillation modes with a mixed character, as observed in evolved low-mass stars, are highly sensitive to the physical properties of the innermost stellar regions. Measuring their properties is therefore extremely important to probe the stellar core, but requires some care. We revisited previous findings and tested how all properties of the mixed modes (period spacings, rotational splittings, mixed-mode widths and heights) can be estimated in a consistent view. From the asymptotic fit of the mixed-mode pattern of hundreds of red giants at various evolutionary stages, we derive asymptotic parameters that are not only very precise, but also accurate. We decipher the complex pattern in rapidly rotating stars, and explain how asymmetrical splittings can be inferred. The variation of the asymptotic gravity offsets ε g along stellar evolution is investigated in detail. Stars with peculiar properties can be identified: buoyancy glitches on the RGB, very rapid core rotation... We also derive generic properties that explain under which conditions mixed modes can or cannot be observed. 129

132 Posters: Stellar physics P35: Resolving Space-Photometry Nyquist Ambiguities from the Ground K. J. Bell 1,2 J. J. Hermes 3,4, Z. Vanderbosch 5,6, D. E. Winget 5,6, M. H. Montgomery 5,6 (1) Max Planck Institute for Solar System Research, Goettingen, Germany. (2) Stellar Astrophysics Centre, Aarhus, Denmark. (3) University of North Carolina, Chapel Hill, NC, USA. (4) Hubble Fellow. (5) University of Texas at Austin, Austin, TX, USA. (6) McDonald Observatory, Fort Davis, TX, USA. Extended short-cadence (1-minute) Kepler and K2 observations have provided the most precise and complete records of white dwarf pulsations ( 10 minute periods) to date. The key advantage of these observations is that they do not suffer cycle-count-ambiguities from gaps that are common with ground-based campaigns. Long-cadence (30-minute) K2 observations are capable of detecting white dwarf pulsations, but these undersampled signals suffer dramatic aliasing against the Nyquist frequency, as well as amplitude suppression. Bell et al. (2017, ApJ, 851, 24) combined the non-ideal data sets of long-cadence K2 light curves with multi-night ground-based photometry to recover accurate frequency solutions at K2-level precision. In this poster, we present the challenges of interpreting these data sets individually and demonstrate how each can inform the correct alias selection in the other. This approach of obtaining modest ground-based follow-up can be widely used to resolve Nyquist ambiguities in other targets of Kepler, K2, and TESS fny Amplitude (%) Frequency (µhz) 130

133 Posters: Stellar physics P36: K2: A Search for Very Red Stellar Objects E. Hartig 1 T. Lebzelter 1, K. Hinkel 2 (1) Department of Astrophysics, University of Vienna, Austria. (2) National Optical Astronomy Observatory, P. O. Box 26732, Tucson, AZ 85726, USA. Continuing the analysis of Long Period Variables (LPVs) observed as part of the Kepler K2 mission we show the latest results. We found that the Kepler K2 High Level Science Product (K2HLSP) Self-Flat-Field method (K2SFF or SFF) corrected the instrumental effects best. An iterative fitting method using sinusoidal functions was developed and evaluated. Furthermore, we present a strategy to properly constrain periods longer than the observational time basis using rms-error minimization. To check the results of this method, we applied it to a 33 d long dataset (1560 data points) of EP (Kepler K2 Campaign 0) for which a ground based period of 730 d is available. The output from our method, 763 d, is in excellent agreement. From the Kepler K2 Campaign 2 we analysed a total of 41 targets data that are suspected or known LPVs. The d of observations provided roughly 3500 data points. We searched for the SFF sinusoidal fit at the global rms-minimum and compared the periods with the available ASAS periods. In this way we defined the error range which could be applied to the rest of the targets. The preliminary results are presented in the poster. 131

134 Posters: Stellar physics P37: Additional modes and cyce-to-cycle variations in non-blazhko RR Lyrae stars J. M. Benkő 1 J. Jurcsik 1, A. Derekas 2,1 (1) Konkoly Observatory, MTA CSFK, Budapest, Hungary. (2) ELTE Eötvös Loránd University, Gothard Astrophysical Observatory, Szombathely, Hungary. At the end of the 19th century, when the pulsating variables have been discovered, seeing their accurately reproducing light curves, it was even suggested that they could be the basis of time measurement as standard oscillators. With the development of stellar pulsation and evolution theories it became evident that the periods of classical pulsating variable stars (Cepheids, RR Lyrae) are changing during their evolution. Short-term or cycle-to-cycle variations have never been included in standard pulsation codes, however, several authors have suggested possible irregular changes in the period and/or amplitude on various theoretical bases. The first direct evidence for a random period jitter on a radially pulsating star has been reported recently for V1154 Cyg, the only classical Cepheid of the original Kepler field. Similar phenomenon was mentioned for CM Ori a non-blazhko RR Lyrae star observed by the CoRoT space telescope. In both cases the detected period variations were about some thousandths or ten thousandths of the pulsation periods. Such a small difference could be detect only in precise uninterrupted data. In this presentation I show our study on the Kepler non-blazhko RR Lyrae sample. We analysed long and short cadence Kepler light curves with different ways (such as studying their Fourier spectra, the Fourier amplitude and phase variation functions, the O C diagrams and their Fourier contents etc.) and detected significant cycle-to-cycle variations both in amplitudes and phases of the light curves. The primary reason of these variations is the low amplitude additional modes which appear in the studied spectra. In other words, we found at least temporarily appearing additional modes for most studied RR Lyrae stars. The characteristics of the phenomenon suggest the properties of the chaotic solutions found in the Florida-Budapest hydrodynamical code. 132

135 Posters: Stellar physics P38: Toward robust mapping of instability strips: a new numerical method for finding non-adiabatic eigenfrequencies J. Goldstein 1 R. H. D. Townsend 1, E. G. Zweibel 1,2 (1) Department of Astronomy, University of Wisconsin-Madison, USA. (2) Department of Physics, University of Wisconsin-Madison, USA. Stellar pulsational instabilities can be determined by calculating eigenfrequencies of the linear non-adiabatic pulsation equations. A standard technique is to adopt adiabatic eigenfrequencies as initial guesses for non-adiabatic ones. However, when the degree of non-adiabaticity in the star is high, this approach can fail. We describe a new numerical method that works well in highly non-adiabatic environments. This Contour Map method finds complex eigenfrequencies of the linear nonadiabatic pulsation equations without a priori knowledge of the adiabatic ones. We demonstrate its implementation in the GYRE code by determining the pulsational instabilities of various stellar models with high luminosity-to-mass ratios, in which non-adiabaticity is significant. The robustness of the Contour Map method makes it the ideal tool for mapping instability strips in the high-luminosity domain of the Hertzsprung-Russell diagram. TESS is expected to find many new pulsating stars in this domain, setting the stage for a productive comparison between theory and observations. 133

136 Posters: Stellar physics P39: Constraining the photon-axion coupling factor in the Sun through oscillation frequency separation ratios E. Corsaro 1 A. Bonanno 1 (1) INAF - Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123, Catania. We present an extensive analysis on the photon-axion coupling factor through the comparison between the latest set of BiSON helioseismic measurements of oscillation frequencies and solar models. We investigate a variety of input physics in the solar models computed with GARSTEC, by including different initial abundances, p-p chain reaction rates, and EOS. We perform a Bayesian analysis of parameter estimation and model comparison based on Bayesian evidence to test the hypotheses of the models and quantify the statistical significance of the axion term. Finally, we compare our results with others presented in the literature. 134

137 Posters: Stellar physics P40: Observing stellar flares in A-type stars observed by Kepler data with Bayesian Blocks and Super-resolution techniques J. Pascual-Granado 1 A. García Hernández 2 (1) Stellar Physics department, Institute of Astrophysics of Andalusia - CSIC, Granada, Spain. (2) Departamento de Física Teórica y del Cosmos, University of Granada, Spain. Theoretical models predict a very thin, if any, convective envelope in A-type stars but some observations point to a convective envelope that might be effective showing the effects of magnetic activity. The efforts to shed some light into this puzzle have been inconclusive. Most of the results regarding flares detection in the literature are based on a set of ad-hoc criteria that are verified manually without any physical foundation. We introduce here an automatic detection pipeline based on Bayesian Blocks detection and super-resolution techniques (i.e. wavelet decomposition). The algorithm is self-consistent and capable to detect a flare candidate and reject false positives providing at the same time physical parameters that can be useful for the characterization of stellar activity in A-type stars, but not limited to these kind of targets. Here we will introduce the algorithm, and using a sample of Kepler stars we will show first results and the prospects for future studies regarding magnetic activity in A-type stars applying this algorithm to the data gathered with the TESS satellite. 135

138 Posters: Stellar physics P41: On the use of the Shannon s information entropy to estimate stellar densities J. C. Suárez 1,2 L. M. Sarro 3, A. Moya 4,1, A. García Hernández 1, M. A. Mendoza 1 (1) Dept. F Fisica Teórica y del Cosmos. Universidad de Granada Granada, Spain. (2) Instituto de Astrofísica de Andalucía. Glorieta de la Astronomía s/n Granada, Spain. (3) Dpto. Inteligencia Artificial, UNED, c/ Juan del Rosal 16, Madrid, Spain. (4) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT, United Kingdom. I will present a simple yet powerful method based on Shannon s entropy to detect frequency patterns in the oscillation spectra. In particular we will seek for the so-called large separation, which is proportional to the stellar mean density. Due to its simplicity, the method might easily be implemented in automated pipelines, e.g. those providing precise values of the mass, radius, and age, which will run in space missions like TESS or PLATO. I will show the results for the Sun, some solar-like stars, A-F, main-sequence stars, and discuss the limitations the method and future prospects, in particular regarding the study of other relevant periodicities (small separations, rotational splittings, etc.). 136

139 Posters: Stellar physics P43: Two s a Crowd: Characterising the effect of photometric contamination on the extraction of global asteroseismic parameters in Red-Giant Binaries S. Sekaran 1 C. Johnston 1, A. Tkachenko 1, A. Prsa 2, K. Hambleton 2, P. Beck 3 (1) Instituut voor Sterrenkunde (IvS), KU Leuven, Celestijnenlaan 200D, B-3001 Leuven, Belgium. (2) Department of Astrophysics and Planetary Science, Mendel Science Center, Villanova University, M458c, 800 Lancaster Ave, Villanova PA 19085, USA. (3) Instituto de Astrofísica de Canarias, La Laguna, Tenerife, Spain. The unprecedented precision of the data provided by the Kepler space mission has enabled significant advances in the field of Red-Giant asteroseismology. Intrepid astronomers have been exploiting these high-precision data to test and improve asteroseismic scaling relations (e.g. Huber et al. 2011; Kallinger et al. 2014). Such studies often utilise binarity (e.g. Gaulme et al. 2016), which enables the confrontation of fundamental parameters calculated from scaling relations with the model-independent fundamental parameters extracted from binary dynamics. However, these studies often neglect the effect of the light contribution of the companion on the extracted global asteroseismic parameters of each component. In this study, we present an estimation the impact of a contaminating photometric signal with a distinct background profile, for different simulated Red-Giant binary configurations, on the extracted values of global asteroseismic parameters used as inputs for scaling relations. We investigate the impact of a contaminating signal from: (1) Another Red Giant; (2) a main-sequence solar-like pulsator; and (3) a constant main-sequence star. Our methodology involves the simulation of the light curves of red giants, using a grid of combinations of radius, mass, and effective temperature. ν max and ν are calculated for each unique combination of mass, radius, and temperature from the standard scaling relations. The contaminating signal is then generated as a separate light curve and blended together with the original according to their light ratio. We then perform a standard analysis to extract the pairs of ν max and ν present in the blended light curve. We show that the extracted ν max and ν vary depending on the type of contaminating signal (red giant, solar-like pulsator or constant) and the light ratio, and are different from the uncontaminated case. 137

140 Posters: Stellar physics P45: Radial velocity measurements with the Perek telescope M. Skarka 1 P. Kabáth 1, E. Guenther 2, S. Sabotta 2 (1) Astronomical Institute ASCR, Fričova 298, CZ-25165, Ondřejov, Czech Republic. (2) Thüringer Landessternwarte Tautenburg, D Tautenburg, Germany. The two-meter Perek telescope is the largest telescope in the Czech Republic. It is equipped with a single-slit spectrograph and Ondrejov echelle spectrograph (OES) with high resolution (R 44000). We present the first radial-velocity measurements of K2 exoplanetary candidates and discuss the stability of the spectrograph. We show that OES can be used for TESS ground-based follow-up observations including studying binarity and pulsating stars. 138

141 Posters: Stellar physics P46: Influence of metallicity on the surface effect L. Manchon 1,2 K. Belkacem 2, R. Samadi 2, T. Sonoi 2,3, J. P. C. Marques 1, H.-G. Ludwig 4,5, E. Caffau 5 (1) Institut d Astrophysique Spatiale, Université Paris-Sud, Orsay, France. (2) LESIA, Observatoire de Paris, PSL Research University, CNRS, Université Pierre et Marie Curie, Université Denis Diderot, Meudon, France. (3) Astronomical Institute, Tohoku University, 6-3 Aramaki Aza-Aoba, Aoba-ku Sendai, , Japan. (4) Zentrum für Astronomie der Universität Heidelberg, Landessternwarte, Königstuhl 12, D Heidelberg, Germany. (5) GEPI, Observatoire de Paris, PSL Research University, CNRS, Université Denis Diderot, Sorbonne Paris Cité, 5 Place Jules Janssen, Meudon, France. Modern asteroseismic measurements enable us to probe stellar interiors with a very high degree of accuracy by comparing the observed and modeled frequencies. However, the latter suffers from systematic errors, called surface effects, related to the poor 1D modeling of the uppermost layers of stars, especially the exclusion of turbulent pressure. Previous works has been done using grids of 3D hydrodynamical simulations in order to correct surface effect, but without considering the effect of metallicity. In this work, we aim at studying its impact on the surface effect, across the Hertzsprung Russell diagram, and include it in empirical corrections models. We computed a grid of patched 1D stellar models with the stellar evolution code CESTAM in which poorly modeled surface layers are replaced by averaged stratification computed with the 3D hydrodynamical code CO 5 BOLD. We found that the metallicity has a strong impact on the surface effect and cannot be neglected. We found that a correct way of accounting for it is to consider the surface mean Rosseland opacity. It allowed us to give a theoretical justification of the variations of the amplitude of the surface effect as a function of T eff, log g and κ. Finally, we provide prescriptions for the fitting parameters of the most commonly used correction functionals. In conclusion, we demonstrate that the impact of the metallicity through the mean Rosseland opacity must be taken into account when studying and correcting the surface effect. 139

142 Posters: Stellar physics P47: Stagger p-drive: studying excitation and damping of p-mode oscillations with 3D simulations R. Collet 1 Y. Zhou 2 (1) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University. (2) Research School of Astronomy and Astrophysics, Australian National University. Modern 3D hydrodynamic simulations of stellar surface convection provide a powerful tool for constructing realistic model stellar atmospheres and improving the accuracy of spectroscopic and photometric analyses. In addition, 3D simulations can also be used to study the mechanisms of excitation and damping of oscillations propagating through stellar interiors to the stellar surface. In 3D hydrodynamic simulations of the outer layers of late- and solartype stars, convection and p-mode oscillations emerge naturally from the numerical solution of the radiation-hydrodynamics equations. However, because of the typical simulation setup, (e.g. limited spatial extent of the simulation domain, periodic boundaries horizontally, constant pressure at bottom boundary,) usually, only some of the natural oscillation modes are populated while others are buried in noise. Here, we propose a novel approach to pick out such hidden modes by applying a low-amplitude periodic pressure drive at the right frequency at the bottom of 3D simulations. In this poster contribution, we present some preliminary results from the analysis of the excitation and damping of p-mode oscillations in such p-drive simulations carried out with the 3D radiation-hydrodynamic Stagger code. 140

143 Posters: Stellar physics P48: HR 7322: A benchmark for stellar evolution A. Stokholm 1 (1) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Denmark. HR 7322 is a bright F6 subgiant star in the Kepler field, which has been used as a comparison star in spectroscopy and photometry. HR 7322 has not been the subject of detailed studies before, but using interferometry and asteroseismology we have made an in-depth analysis of HR The derived stellar parameters are used in order to find the constraints needed for stellar modelling and thus to test and improve our current models of stellar structure and evolution. 141

144 Posters: Stellar physics P49: Damping rates and frequency corrections of LEGACY stars G. Houdek 1 M. N. Lund 1, R. Trampedach 2, R. Handberg 1, J. Christensen-Dalsgaard 1 (1) Stellar Astrophysics Centre, Aarhus University, DK 8000 Aarhus C, DK. (2) Space Science Institute, 4750 Walnut Street, Boulder, CO 80301, USA. We model damping rates and modal frequency corrections for twelve selected Kepler LEGACY stars covering a large range of surface temperatures and surface gravities. The linear stability calculations adopt the nonlocal, time-dependent convection model by Gough (1977), implemented consistently in both the stellar equilibrium-structure modelling and in the nonadiabatic pulsation calculations. The global stellar parameters and depths of surface convection zones are obtained from frequency-calibrated ASTEC evolution calculations (Silva Aguirre et al 2017) and the nonlocal convection parameters are calibrated against a grid of 3D hydrodynamical simulations by Trampedach et al. (2013) and LEGACY linewidth measurements by Lund et al. (2017). We find good agreement between linewidth data and damping rates and, at the same time, also between the 3D and 1D results of turbulent pressure profiles and anisotropies of the turbulent velocity field. The absolute modal frequency corrections, relative to a standard adiabatic pulsation calculation, increase with surface temperature and surface gravity. 142

145 Posters: Stellar physics P50: Modelling the rotating red giant star KIC using Kepler data D. Pricopi 1 D. R. Constantin 1, M. D. Suran 1 (1) Astronomical Institute of the Romanian Academy, Bucharest, Romania. This work deals with the precise modelling of the rotating red giant star KIC We have analyzed oscillations of the red giant star KIC observed by NASA Kepler satellite. The data consists of the first eleven quarters of science operations of Kepler which cover about 27 months. The high signal-to-noise ratio (S/N) and continuous data sets allow us to accurately extract the oscillation parameters from the power spectrum. We have chosen the KIC values to constrain the effective temperature, metallicity and surface gravity of the best fitting model of KIC We have measured the observed rotational splittings in the nonradial dipole mixed modes and we have found the maximum value of the rotational splitting in the g-m mixed modes as µhz. The link between observed rotational splittings and the rotating core is investigated. By fitting a model of internal rotation profile to observed splittings, we have estimated the size of rigid rotating core as about of stellar radius. Also, we have found differential rotation in the convective envelope as a signature of angular momentum transport from core to envelope. The mean observational period spacing for the l=1 mixed modes of about 61 s suggests that this red giant branch star is in the shell hydrogen-burning phase. 143

146 Posters: Stellar physics P51: Investigating the Metallicity-Mixing Length Relation L. S. Viani 1 S. Basu 1, J. Ong J. M. 1, A. Bonaca 2, W. J. Chaplin 3,4 (1) Department of Astronomy, Yale University, New Haven, CT, 06520, USA. (2) Department of Astronomy, Harvard University, Cambridge, MA, 02138, USA. (3) School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, UK. (4) Stellar Astrophysics Centre (SAC), Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. Stellar models typically use the mixing length approximation as a way to implement convection in a simplified manner. While conventionally the value of the mixing length parameter, α, used is the solar calibrated value, many studies have shown that other values of α are needed to properly model stars. This uncertainty in the value of the mixing length parameter is a major source of error in stellar models and isochrones. Using asteroseismic data, we determine the value of the mixing length parameter required to properly model a set of about 450 stars ranging in log g, T eff, and [Fe/H]. The relationship between the value of α required and the properties of the star is then investigated. For Eddington atmosphere, non-diffusion models, we find that the value of α can be approximated by a linear model. We also discuss how this changes isochrones. 144

147 Posters: Stellar physics P52: Characterisation of pulsations in γ Doradus candidate stars using high resolution spectroscopy and photometry T. R. Shutt 1 E. Brunsden 2, K. R. Pollard 3, P. F. L. Maxted 4 (1) Department of Physics, University of York, United Kingdom. (2) Department of Physics, University of York, United Kingdom. (3) Department of Physics and Astronomy, University of Canterbury, New Zealand. (4) School of Chemical and Physical Sciences, Keele University, United Kingdom. We present a summary of high resolution spectroscopy techniques carried out under the remit of the MUSICIAN program at The University of Canterbury, New Zealand, incorporating results from a new multidisciplinary analysis of two γ Doradus candidate stars: HD and HD Over 250 spectra were gathered for analysis using the ground based high resolution HER- CULES spectrograph at the University of Canterbury Mt John Observatory. The spectra for each star were cross-correlated with synthetic spectra to produce line profiles and further augmented with photometry from the WASP archive and HIPPARCOS catalogue for frequency and mode analysis. Multiple pulsation frequencies were identified with confidence for each star, and further characterised with best-fit modes allowing categorisation of the candidates as bona fide γ Doradus stars. The results are presented here, with fundamental stellar properties for each star determined during the analysis. 145

148 Posters: Stellar physics P54: Choosing Wisely: The Effects of Algorithms and Observing Windows on Rotation-Activity Studies (1) Florida Gulf Coast University, USA. D. Buzasi 1 H. Andrews 1, Z. Dominguez 1 The Kepler mission observed 200,000 stars in the same field nearly continuously for over four years, generating an unparalleled set of stellar rotation curves and new insights into the correlation between rotation periods and photometric variability, while the continuation of Kepler in the guise of K2 has allowed us to examine a comparable stellar sample drawn from a new population. However, K2 observed each field for at most 90 days, and TESS will have time windows as short as 27 days. The quasi-periodic nature of rotational light curves, combined with the potential presence of additional periodicities not due to rotation, complicates the analysis of these time series, particularly with such short observing windows. In this work, we apply a wide range of algorithms to light curves produced by a number of popular K2 pipeline products to better understand the advantages and limitations of each approach and provide guidance for the most reliable and most efficient analysis of TESS stellar data. We also study the impact of shorter observing windows on the characterization of photometric variability and the implications for comparison of data between TESS and earlier missions. 146

149 Posters: Stellar physics P56: Constraining the Magnetic Activity Distribution on Other Stars using Asteroseismology A. E. L. Thomas 1,2 W. J. Chaplin 1,2, G. R. Davies 1,2, R. Howe 1,2, A. R. G. Santos 3 (1) School of Physics and Astronomy, University of Birmingham, UK. (2) Stellar Astrophysics Centre, Aarhus University, Denmark. (3) Space Science Institute, University of Porto, Portugal. The effects of magnetic activity on oscillation properties has been observed on the Sun, and more recently on other solar-type stars thanks to missions like CoRoT and Kepler. We see evidence for temporal variations in the frequencies of acoustic modes, which are associated with stellar activity cycles. High resolution imaging of the Sun tells us that magnetic activity is concentrated in bands of active latitude and we expect similar manifestations on the surfaces of other solar-type stars. Estimating the latitudinal dependence of magnetic activity is difficult but thanks to the nearly-continuous lightcurves from Kepler, asteroseismology provides an opportunity to constrain the distribution on other stars. This would give us a way to explore dynamo models in conditions that are different from the Sun. With a non-homogeneous distribution of magnetic activity, modes of different angular degree and azimuthal order (which propagate in different regions within the star) will experience different frequency shifts. We present a method which predicts the distribution of surface magnetic activity using the frequency shifts of monopole and dipole modes. Our model fits for minimum and maximum latitudes describing a band of activity wrapped around the star. We apply it to the frequencies of the solar-type star KIC , which was observed during the nominal Kepler Mission. We find that the near-surface activity is distributed more widely in latitude on this star than is the case for the Sun. 147

150 Posters: Stellar physics P57: Predicting radial-velocity jitter induced by stellar oscillations based on Kepler data J. Yu 1,2 D. Huber 3,1,4,2, T. R. Bedding 1,2, D. Stello 5,1,2 (1) Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (3) Institute for Astronomy, University of Hawai i, 2680 Wood-lawn Drive, Honolulu, HI 96822, USA. (4) SETI Institute, 189 Bernardo Avenue, Mountain View, CA 94043, USA. (5) School of Physics, University of New South Wales, NSW 2052, Australia. Radial velocity jitter due to intrinsic stellar variability introduces challenges when charactering exoplanet systems, in particular, when studying the exoplanetary signals of small planets (sub-neptune) orbiting solar-type stars. We aim to predict for dwarfs and giants the jitter due to stellar oscillations, based on global oscillation parameters measured with Kepler data. We fit the jitter in terms of the following sets of stellar parameters: (1) Luminosity, mass, and effective temperature: the fit returns precisions of 17.9% and 27.1% for dwarfs and giants, respectively. (2) Luminosity, effective temperature, and surface gravity: The precisions are the same as using the previous parameter set. (3) Surface gravity and effective temperature: we obtain a precision of 22.6% for dwarfs and 27.1% for giants. (4): Luminosity and effective temperature: the precision is 47.8% for dwarfs and 27.5% for giants. Our method will be valuable for anticipating the potential radial-velocity stellar noise level of exoplanet host stars to be found by the TESS and PLATO space missions, and thus can be useful for their follow-up spectroscopic observations. Our method can also be used to set a prior for the jitter term as a component when modeling the Keplerian orbits of the exoplanets. 148

151 Posters: Stellar physics P58: A simple tool for calculating centrifugal deformation starting from 1D stellar models (1) LESIA, Observatoire de Paris, France. P. Houdayer 1 D. R. Reese 1 In this contribution, we describe a tool which is able to calculate centrifugal deformation starting from a 1D stellar model, for conservative (i.e. cylindrical) rotation profiles. This tool applies an iterative approach based on the Self-Consistent Field (SCF) method while preserving the pressure profile as a function of density. The resultant model is suitable for stellar pulsation calculations, thus making this tool suitable for parametric asteroseismic investigations. It can also be used to calculate the deformation of rapidly rotating planets such as Jupiter and Saturn. 149

152 Posters: Stellar physics P59: Asteroseismic modelling of sub giants: key to accurate stellar ages Tanda Li 1,2 Hans Kjeldsen 2, Yaguang Li 3, Tim Bedding 1,2, Dennis Stello 4 (1) Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW 2006, Australia. (2) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (3) Department of Astronomy, Beijing Normal University, Beijing, China. (4) School of Physics, University of New South Wales, Australia. Stellar ages from theoretical stellar models are strongly affected by the uncertainties in the input physics. The mixed modes excited in low-mass subgiants are sensitive to the internal structures and their amplitude are strong for high S/N detections. Modelling of individual subgiants hence offers the best the chance for precise stellar ages. Our modelling of the SONG target mu Herculis shows that its age is much less dependent than main-sequence stars on Initial helium, metallicity, and the mixing-length parameter. We have found similar results from modelling 42 Kepler subgiants. To be specific, changing either the mixinglength parameter or the initial helium abundance does not change the age systematically. Moreover, changing the input metallicity by 0.1 dex changes only changes the age by less than 10 percent for most stars (see attached figure). Thus, the seismic modelling of subgiants can significantly reduce the model dependences and give accurate stellar ages. 150

153 Posters: Stellar physics P60: The difference is in the detail: light curve shapes of RRab stars from Kepler/K2 data J. K. S. S. (1), K. K. (1), E. U. (1), P. S. (1) 1 (1) Department of Physics, University of Antwerp, Belgium. RR Lyrae stars, and in particular those pulsating in the radial fundamental mode, can be easily identified by their characteristic light curve shape. The details of this shape host partly unexplored information about the star. Using Kepler and K2 photometry, we investigate how the light curve shape of RRab stars correlates with various properties. 151

154 Posters: Stellar physics P61: On the limits of seismic inversions for radial differential rotation of solar-type stars A. R. G. Santos 1 M. J. Thompson 2, S. Mathur 3, R. A. García 4 (1) Space Science Institute, Colorado, USA. (2) National Center for Atmospheric Research, Colorado, USA. (3) IRFU, CEA, Université Paris-Saclay, France. (4) Instituto de Astrofísica de Canarias, Tenerife, Spain. Among other stellar properties, seismic data contains information on stellar internal rotation, which plays an important role on stellar dynamo models. Helioseismology has been successful in the characterization of internal rotation in the Sun. However, due to the uncertainties on the observations and on stellar models, determining internal rotation in stars other than the Sun, in particular solar-type stars, has been challenging. In this work, using artificial rotational splittings, we explore the limitations on the constraining of internal rotation profiles through the implementation of a regularized least squares inversion method. We further test the impact of using surface rotation estimates (for instance, inferred from spot modulation of stellar light curves) on the rotation profile determination. 152

155 Posters: Stellar physics P62: Further constraints on the age and helium abundance of NGC 6791 from modeling of the asteroseismic oscillations. Jean McKeever 1 Sarbani Basu 1 (1) Department of Astronomy, Yale University. NGC 6791 is an old ( 8 Gyr), metal rich ([Fe/H] 0.3) open cluster in which previous studies have indicated also has a high helium abundance. The cluster happened to lie within the Kepler field of view and had unprecedented light curves for many of the red giant branch (RGB) stars in the cluster. Asteroseismic studies have constrained the age through grid based modeling of the global asteroseismic parameters ( ν and ν max ). However, with Kepler data it is possible to do detailed asteroseismology of individual mode frequencies to better constrain the stellar parameters, something that has not been done for these cluster stars as yet. In this work, we use the radial (l = 0) and quadrupole (l = 2) modes in 40 hydrogen shell burning RGBs to better constrain the age and initial helium abundance (Y 0 ). We have created a grid of stellar evolution models using MESA that span the expected ranges of mass, initial [ Fe/H], Y 0, and mixing length in the cluster RGBs. We compute model oscillation frequencies at each timestep along the RGB in the expected log g range of our stars with the pulsation code GYRE. The distribution of parameters for all the giants are then combined to create a final probability distribution for age and helium of the entire cluster. 153

156 Posters: Stellar physics P63: Chaotic pressure modes in rapidly rotating stars B. Evano 1,2 F. Lignières 1, B. Georgeot 2 (1) Institut de Recherche en Astrophysique et Planétologie, Université Paul Sabatier, France. (2) LPT Laboratoire de Physique Théorique, Université Paul Sabatier, France. The high-frequency spectrum of p-mode in rapidly rotating stars is investigated numerically and interpreted using a ray-based asymptotic theory. The spectrum is known to be a superposition of sub-spectra associated with the different structures of the ray dynamics phase space, the two most visible being the island mode and the chaotic mode sub-spectra (Lignieres & Georgeot 2009). We present new and unexpected regular frequency spacings found among chaotic modes and interpret them using periodic orbit theory (Gutzwiller trace formula). The consequences for the identification of p-modes in delta Scuti stars are discussed. 154

157 Posters: Stellar physics P64: Is the single-referee review process broken? (1) UNSW-Sydney, Australia. D. Stello 1 In this poster I will discuss the currently most common way of peer review, which typically uses just one referee. This will include discussion on whether editors exercise their role as opposed to letting referees be the decision maker. With recent examples, I will show how random responses and editor outcomes can seem to be when submitting the same paper to different journals. 155

158 Posters: Stellar physics P66: γ Doradus stars as test of angular momentum transport models R-M. Ouazzani 1 J. P. Marques 2, M-J. Goupil 1, S. Christophe 1, V. Antoci 3, S. J. A. J. Salmon 4 (1) LESIA, Observatoire de Paris, PSL Research University, CNRS, Sorbonne Universités, UPMC Univ. Paris 06, Univ. Paris Diderot, Sorbonne Paris Cité, 5 place Jules Janssen, Meudon, France. (2) Univ. Paris-Sud, Institut d Astrophysique Spatiale, UMR 8617, CNRS, Bâtiment 121, 91405, Orsay Cedex, France. (3) Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark. (4) STAR Institute, Université de Liège, Allée du 6 août 19, 4000 Liège, Belgium. Helioseismology and asteroseismology of red giant stars have shown that distribution of angular momentum in stellar interiors, and its evolution with time remains an open issue in stellar physics. Owing to the unprecedented quality and long baseline of Kepler photometry, we are able to seismically infer internal rotation rates in γ Doradus stars, which provide the main-sequence counterpart to the red-giants puzzle. Here, we confront these internal rotation rates to stellar evolution models which account for rotationally induced transport of angular momentum, in order to test angular momentum transport mechanisms. On the one hand, we used a stellar model-independent method developed by Christophe et al. in order to obtain accurate, seismically inferred, buoyancy radii and near-core rotation for 37 γ Doradus stars observed by Kepler. We show that the stellar buoyancy radius can be used as a reliable evolution indicator for field stars on the main sequence. On the other hand, we computed rotating evolutionary models of intermediate-mass stars including internal transport of angular momentum in radiative zones, following the formalism developed by Zahn and Maeder, with the cestam code. This code calculates the rotational history of stars from the birth line to the tip of the RGB. The initial angular momentum content has to be set initially, which is done here by fitting rotation periods in young stellar clusters. We show a clear disagreement between the near-core rotation rates measured in the sample and the rotation rates obtained from the evolutionary models including rotationally induced transport of angular momentum following [?]. These results show a disagreement similar to that of the Sun and red giant stars in the considered mass range. This suggests the existence of missing mechanisms responsible for the braking of the core before and along the main sequence. The efficiency of the missing mechanisms is investigated. The transport of angular momentum as formalized by Zahn and Maeder cannot explain the measurements of near-core rotation in main-sequence intermediate-mass stars we have at hand. 156

159 Posters: Stellar physics P67: Seismic Probing of the first dredge-up event and tidal interactions in red-giant binaries P. G. Beck 1 T. Kallinger 2, S. Mathis 3, A. Palacios 4, K. Pavlovski 5, F. Gallet 6, R. A. Garcia 3 (1) Instituto de Astrofisica de Canarias, Tenerife, Spain. (2) Institut für Astrophysik, Universität Wien, Austria. (3) Commissariat à l Énergie atomique et aux Énergies, Paris-Saclay, France. (4) Université de Montpellier, France. (5) Department of Physics, University of Zagreb, Croatia. (6) Observatoire de l université de Genève, Switzerland. Binaries in spectroscopic systems provide a homogeneous set of stars. Differences between parameters, such as age or initial conditions, which otherwise would have strong impact on the stellar evolution and blur the comparison on a star-to-stars basis, can be neglected. In this poster, we present the comprehensive analysis of KIC , constituted of two red giants of 1.4±0.1Mo. The masses of the two components differ only by 1.5±0.5%. We show that both stars are located in the short-lived phase of the first dredge up on the red-giant branch when the convective envelope reaches the deepest penetration into the star. While asteroseismology allows characterising the primary component well, the large difference in lithium abundance between the two otherwise very similar components is used to test stellar evolutionary models. From a study of tidal interactions in the ensemble of red-giant binary systems, we conclude that the close resemblance of the surface rotation and orbital period is a coincidence and does not correspond to a sign of spin synchronisation. The comparison of the rotation period inferred from asteroseismology and surface rotation indicates that the convective envelope is rotating rigidly. Evidence for the detection of the power excess of the secondary component in the composite power spectrum is presented. Therefore, KIC is one of the prototypes of binary systems with two oscillating red-giant components. Such seismic systems, which offer many constraints, can be employed as benchmark object to be used to calibrate evolutionary models and stellar ages. Related papers: Beck, Kallinger, Pablovski, et al. 2018a, A&A 612, A22 Beck, Mathis, Gallet, et al. 2018b, MNRAS, under revision 157

160 Posters: Stellar physics P68: Asteroseismology of DBVs with K2-precision light curves Z. Vanderbosch 1 J. J. Hermes 2, M. H. Montgomery 1, D. E. Winget 2 (1) University of Texas at Austin. (2) University of North Carolina at Chapel Hill. With recent discoveries from K2 and McDonald Observatory, we now observe pulsations in 39 helium atmosphere white dwarfs (DBs) with spectroscopic effective temperatures between roughly 21,000 31,000 K, a range 3,000 K wider than what current theory predicts for the DB instability strip (22,000 29,000 K). While spectroscopic temperatures are often unreliable for DBs due to the potential for undetected trace hydrogen in low-s/n spectra, independent relative temperatures may also be obtained from a detailed asteroseismic analysis of their identifiable eigenmodes. Until now, just two pulsating DBs, KIC & PG , have benefited from the precision of Kepler/K2 observations. Here, we present a preliminary asteroseismic analysis of five additional pulsating DBs observed by K2, four of which are newly discovered pulsators. Some of these objects exhibit rotational splittings, allowing for a measurement of both the rotation period of the white dwarf as well as identification of the eigenmodes. We place these objects into the context of all known pulsating and non-pulsating DBs to provide an update on the empirical limits of the DB instability strip. Lastly, we report on the development of a spectroscopic program to put better constraints on the [H/He] abundances for these objects. TASC4-KASC11 Talk/Poster Abstract Asteroseismology of DBVs with K2 -precision light curves With recent discoveries from K2 and McDonald Observatory, we now observe pulsations in 39 helium atmosphere white dwarfs (DBs) with spectroscopic effective temperatures between roughly 21,000 31,000 K, a range 3,000 K wider than what current theory predicts for the DB instability strip (22,000 29,000 K). While spectroscopic temperatures are often unreliable for DBs due to the potential for undetected trace hydrogen in low-s/n spectra, independent relative temperatures may also be obtained from a detailed asteroseismic analysis of their identifiable eigenmodes. Until now, just two pulsating DBs, KIC & PG , have benefited from the precision of Kepler/K2 observations. Here, we present a preliminary asteroseismic analysis of five additional pulsating DBs observed by K2, four of which are newly discovered pulsators. Some of these objects exhibit rotational splittings, allowing for a measurement of both the rotation period of the white dwarf as well as identification of the eigenmodes. We place these objects into the context of all known pulsating and non-pulsating DBs to provide an update on the empirical limits of the DB instability strip. Lastly, we report on the development of a spectroscopic program to put better constraints on the [H/He] abundances for these objects

161 Posters: Stellar physics P69: Overfitting and correlations in model fitting with frequency ratios I. W. Roxburgh 1 (1) Astronomy Unit, School of Physics and Astronomy, Queen Mary University of London, Mile End Road, London E1 4NS, UK. I consider two issues of importance when comparing separation ratios deduced from an observed frequency set with those of stellar models. Combining the r 01 and r 10 ratios into a single series r 010 is overfitting the data which can lead to spurious results. Secondly, since the r 02 ratios are strongly correlated with r 01 and r 10 ratios, they should be combined into a single series r 012 (or r 102 ) and models and observation compared using the covariance matrix cov 012 (or cov 102 ) of the combined set. I illustrate these points by comparing the revised Legacy Project data with my results on 16 Cyg A & B and KIC

162 Posters: Stellar physics P70: Dipolar modes and the size of helium core on red giants Tao Wu 1,2,3 Yan Li 1,2,3,4 (1) Yunnan Observatories, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, , P. R. China. (2) Key Laboratory for the Structure and Evolution of Celestial Objects, Chinese Academy of Sciences, 396 Yangfangwang, Guandu District, Kunming, , P. R. China. (3) Center for Astronomical Mega-Science, Chinese Academy of Sciences, 20A Datun Road, Chaoyang District, Beijing, , P. R. China. (4) University of Chinese Academy of Sciences, Beijing , China. Asteroseismology is a powerful tool for determining stellar fundamental parameters and probing stellar inner structure and status and further to discovering the relative physical processes in stellar evolutions. Thanks to the uninterrupted and unexpected high-precise observations of Kepler mission, the research of red giant asteroseismology has been entered a new era. As a result in mode coupling between non-radial p- and g-mode, the dipolar modes of red giants contains the oscillation properties of both p- and g-mode in outer envelope (p-mode cavity) and the inner core (g-mode cavity), respectively. Such coupled modes are called as p- and/or g-dominated-mixed-mode, according to their oscillation properties. For g-dominated-mixed-mode, most of oscillation energy (more than 80%) is trapped in the inner core (i.e., helium core). While, for p-dominated-mixed-mode, it is approximately averagely trapped in the inner core (40%) and the outer envelope (60%). In the talk, we will illustrate that how to accurately determine the size of helium core on red giants from dipolar modes via asteroseismology. 160

163 Posters: Space missions

164 Posters: Space missions P04: Extending asteroseismology to extragalactic Cepheids with K2 László Molnár 1 Emese Plachy 1, András Pál 1,2 (1) Konkoly Observatory, MTA CSFK, Budapest, Hungary. (2) Department of Astronomy, Eötvös University, Budapest, Hungary. The Kepler space telescope observed the Local Group member, IC1613, during Campaign 8 of the K2 mission. This irregular dwarf galaxy contains more than a hundred classical and a handful of Type II Cepheid stars that are accessible for Kepler. While these stars have been thoroughly studied for the purposes of near-field cosmology, their light curve properties and mode content received much less attention. We extracted differential-image photometry of a large number of stars from the K2 observations, providing the first ever continuous light curves of extragalactic Cepheids. While most stars appear to be singlemode pulsators from these photon-limited light curves, we were able to detect additional, presumably non-radial modes in a few overtone stars. With these detections, we extended the reach of stellar pulsation studies and asteroseismology to 700 kpc, a ten-fold increase compared to the distance of the Magellanic Clouds. 162

165 Posters: Space missions P11: TESS/SONG observations S. Frandsen 1 (1) Stellar Astrophysics Centre, Aarhus University, Denmark. The missions, which are the reason that we are here, have lead to great progress in our knowledge of exoplanets and stellar interiors. What can a small project like the Stellar Observation Network Group network add? I present a few answers to this question and some suggestions for supplementary data that can be observed with the evolving SONG network. 163

166 Posters: Space missions P17: Delphini-1 - Aarhus University s First Satellite K. Trelborg 1 V. Antoci 1, H. Kjeldsen 1 (1) Stellar Astrophysics Center, Aarhus Univeristy, Denmark. At Aarhus University, we have established the AUSAT programme, which is a strategic project aiming at assessing, designing and developing nano-satellites for research and education. This is done across departments at Science and Technology and in close collaboration with industry partners. The first Aarhus University satellite - a proof-of-concept project is Delphini-1. The main purpose is to assemble, test and operate a scientific satellite. It will thus be paving the road for future astronomical satellites in the Aarhus University satellite program. The Delphini-1 satellite is a 10 x 10 x 10 cm CubeSat with a camera payload - the 1U- NanoEye. Our poster will review the Delphini-1 satellite and discuss the science we can carry out with such a small instrument. Even though Delphini-1 was designed as a proofof-concept project we will asses whether or not simple photometric measurements of bright stars can be obtained. If successful it will be the first single unit CubeSat to do astronomical measurements. 164