Characterizing Small Planets via Spectroscopy of their Host Stars Johanna Teske in collaboration with Robert Wilson, Steven Majewski, Katia Cunha, Verne Smith, Diogo Souto, Chad Bender, Suvrath Mahadevan, Nicholas Troup, Carlos Allende Prieto, Keivan Stassun Cayman Unterborn, Wendy Panero, Scott Hull, Jennifer Johnson Stephen Shectman, Paul Butler, Jeff Crane, Ian Thompson, Sharon Wang
A few of my other projects Teske et al. in prep Thorngren et al. 2016 Kama et al. 2015 Teske et al. in prep
Small Planets Are Diverse* Wolfgang, Rogers, & Ford 2016? *At least somewhat Lopez-Morales et al. 2016, Zeng, Sasselov, & Jacobsen 2016
How do we learn about exoplanet Planet mass and radius composition? Stellar spectra Stellar activity Interior models Gas/ice giants core size Interior composition Super Earths OBSERVATIONS mineralogy tectonics Rocky planets habitability Atmospheric spectra Disk spectra Molecule maps, chemical models Stellar abundances Planet formation Migration history Volatile content evolution Formation conditions Planetesimal composition Spectral retrieval based on Madhusudhan et al. 2014 Chemical abundances NLTE chemistry Thermal (non) inversions Clouds, hazes, etc. Atmosphere dynamics
How do we learn about exoplanet Planet mass and radius composition? Stellar spectra Stellar activity Interior models Gas/ice giants core size Interior composition Super Earths OBSERVATIONS mineralogy tectonics Rocky planets habitability Atmospheric spectra Disk spectra Molecule maps, chemical models Stellar abundances Planet formation Migration history Volatile content evolution Formation conditions Planetesimal composition Spectral retrieval based on Madhusudhan et al. 2014 Chemical abundances NLTE chemistry Thermal (non) inversions Clouds, hazes, etc. Atmosphere dynamics
How do we learn about exoplanet Planet mass and radius composition? Stellar spectra Stellar activity Interior models Gas/ice giants core size Interior composition Super Earths OBSERVATIONS mineralogy tectonics Rocky planets habitability Atmospheric spectra Disk spectra Molecule maps, chemical models Stellar abundances Planet formation Migration history Volatile content evolution Formation conditions Planetesimal composition Spectral retrieval based on Madhusudhan et al. 2014 Chemical abundances NLTE chemistry Thermal (non) inversions Clouds, hazes, etc. Atmosphere dynamics
Data from Palme & Jones 2003; Lodders 2003; Asplund et al. 2009 Why should we believe the star-planet composition connection? The Sun s abundances match those of primitive solar system material Earth s mantle composition & Rcore retrieved more accurately with host star abundance constraints Dorn et al. 2015
Host star
Super-Earth & Neptune hosts Host star K e p l e r! > Dawson & Murray-Clay 2013 Giant planet hosts Adibekyan et al. 2012 Relative Frequency Stars without planets? Planet Radius Buchhave et al. 2014, Schlaufman 2015 see also Winn et al. 2017
Dawson et al. 2015 > 2 R 1.5-2 R < 1.5 R star vs. Period planet 10^[M/H] Short period planets prefer metal-rich stars Mulders et al. 2016 Orbital Period [days] No small, longer period planets around metal-rich stars embryos grow faster Orbital Period [days]
Two Distinct Orbital Period Regimes Inferred from Host Star measured with APOGEE Host star Planet Orbital Period
star vs. Period planet p value Number of Planets Orbital Period [days] Host Star Host Star Wilson, Teske et al. almost submitted :) Orbital Period [days] 300 KOI dwarfs P crit = 8.5 days (~0.08-0.1 AU) Need 0.1 dex precision to detect
> star vs. Period planet dust dust X > gas gas? > X
Jin & Mordasini 2017 based on Fulton et al. 2017 see also Owen & Wu 2017, 2013 star vs. Period planet Planet Radius [R ] Ice Mass Fraction vs. R planet a [AU] Small planets around more metal-rich stars orbit closer in and are predominantly rocky
Host star Mg, Si
Bond+ 2010 see also Delgado Mena+2010 Host star Mg, Si C/O Mg/Si Wide variety in stellar Mg/Si, result in different interior compositions? Planet leftovers as measured from polluted white dwarfs show range in Mg/Si (~0.7-2.3) log g [cm/s 2 ] Number of Stars T eff [K] Mg/Si Xu et al. 2014 Brewer & Fischer 2016
Stellar Chemical Clues as to the Rarity of Exoplanetary Tectonics atmospheric escape and thus Earth-likeness volatile recycling core cooling sustained surface liquid H 2 0 surface temp rock weathering Based on Foley & Driscoll 2016, Fig. 1 Images from ISS, Mysterious Universe, Britannica
Sun Kepler hosts (APOGEE) FGK Stars (Adibekyan) Unterborn et al. (+Teske) 2017 Fc (N/m) x 10 12 Host star Mg, Si Mg/Si affects core size and thus planet density based on Unterborn & Panero 2017 Bulk Planet (Mg+2Si)/Fe Mg/Si affects whether crust sinks or not and thus plate tectonics
Looking Ahead to TESS
Looking Ahead to TESS Magellan II/ PFS du Pont/ APOGEE-2S
Planet Period [days] TESS+Magellan II/PFS2 Looking to collaborate! Planet Radius [R ] Observe TESS Southern CVZ targets, focusing on fainter stars where we can make best use of 6.5m Given realistic plan, could acquire ~25 RVs on ~50 targets or ~80 RVs on ~20 targets, over 2 yrs? RV Semi Amplitude K (m/s) RV Semi-Amplitude [m/s] simulated TESS detections from Sullivan et al. 2015 8 from Sharon Wang Sun like M dwarfs 6 4 60 min 40 min 2 60 min PFS Median PFS Best 0 6 15 min 30 min 40 min < 10 min exposure 8 10 12 V Magnitude V magnitude 14
TESS+du Pont/APOGEE-2S Normalized Intensity Wavelength [Å] from Diogo Souto courtesy Diogo Souto APOGEE has started to break open the M dwarf abundance field! 2018A: Begin pilot CIW program to observe TESS SCVZ, various science cases (one is exoplanets). AS4: Milky Way Mapper. degrees from ecliptic pole Join SDSS-V! from Jen van Saders degrees from ecliptic pole
Knowledge Nuggets Host star abundances can help constrain when/where/from what material the planets formed, and thus their current compositions. Interior compositions and dynamics of small exoplanets are important in determining their Earth-likeness ( habitability ). TESS has the potential to significantly expand our knowledge of (small) planet formation and composition.