Late-Type Stars and Observational Studies Based on SiO and H 2 O Masers Jan., 2018 Kantary Hills Hotel, Chiang Mai, Tailand

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1 Late-Type Stars and Observational Studies Based on SiO and H 2 O Masers Jan., 2018 Kantary Hills Hotel, Chiang Mai, Tailand Se-Hyung Cho, KASI, Korea

Outlines Basic Introduction Studies of Late-Type Stars Mainly Based on Single Dish Survey Observations Monitoring Observations Toward VLBI Key Science Project Based on SD Obs.

2 Outlines Basic Introduction Studies of Late-Type Stars Mainly Based on Single Dish Survey Observations Monitoring Observations Toward VLBI Key Science Project Based on SD Obs. : VLBI studies on the structure and dynamical effect of pulsation from SiO to H2O maser regions Summary and Issues of 1 st Stage KSP Results * Introduction to ALMA results : VY CMa, o Cet

3 Naming of Cosmic Radio Waves by Emission Mechanisms Continuum Thermal continuum by black body radiation, dust, free-free or bound-free emission Non-thermal continuum by synchrotron emission (from high energy particles) Lines (including absorption line) Atomic hyperfine splitting (e.g., 21 cm line of neutral hydrogen) High-level recombination lines from interstellar atom Molecular rotation lines - Thermal emission lines (e.g., carbon monoxide) - Maser lines cf. Lasers Naming by Wavelengths m, cm, mm, submm waves * mm, submm lines from molecular rotation

4 Techniques of Radio Astronomy T. L. Wilson1 2011

5 Maser Molecules Maser Molecules Comets Star Circumstellar SNR Active formation envelopes galaxies H 2 O Y Y Y CH 3 OH Y SiO Y Y OH Y Y Y Y Y HCN Y H 2 CO Y Y NH 3 Y CN Y Y

Energy Level Diagrams of H 2 O and SiO Molecules SiO Energy Levels main maser transitions for ES H 2 O 6 16-5 23 22.

6 Energy Level Diagrams of H 2 O and SiO Molecules SiO Energy Levels main maser transitions for ES H 2 O GHz SiO v=1, J= GHz v=2, J= GHz v=1, J= GHZ v=1, J= GHz

7 Receiver Overview of NARIT TNRT 40m Tel. From Phrudth s PPT

Single Dish Performance of 21 m Telescopes of Yonsei, Ulsan, Tamna : HPBW / Aperture efficiencies Home page: http://kvn-web.kasi.re.kr/index.

8 Single Dish Performance of 21 m Telescopes of Yonsei, Ulsan, Tamna : HPBW / Aperture efficiencies Home page: Site Yonsei Ulsan Tamna Band (GHz) HPBW (arcsec) Aperture Efficiency (%) Beam Efficiency (%)

9 Angular resolution and Baseline Sensitivity Baseline B (km) θ HBPW (mas) 22 GHz 43 GHz 86 GHz 129 GHz Home page: Status Report KY-KU KU-KT KT-KY B.S: Integration time of 100sec (K-band), 60sec (Q-band), 30sec (W/Dband), and the bandwidth of 256MHz Frequency Band Frequency T Range sys SEFD Gain ΔS(BL) ΔImage (GHz) (K) (Jy) (K/Jy) (mjy) (mjy/beam) K Q W D

Late-Type Stars Habing 1996, A&AR 97 Most stars, those with main-sequence mass, 1-8 M, finally reach a phase of Asymptotic Giant Branch (AGB), where they combine a high luminosity (3000 L and higher)

10 Late-Type Stars Habing 1996, A&AR 97 Most stars, those with main-sequence mass, 1-8 M, finally reach a phase of Asymptotic Giant Branch (AGB), where they combine a high luminosity (3000 L and higher) and a low effective temperature (below 3000 K): luminous red giants. During the AGB phase the stars begin to expel matter at a high rate (10-7 to 10-4 M /yr). The process lasts only for about 10 5 yr but enough to build a circumstellar envelope around central star. The relation between central stars and envelope & evolutionary process from AGB to PN? Herwig 2005, Ann Rev A&Ap

11 AGB stars: oxygen and carbon abundance in envelopes Oxygen-rich (O>C, typical molecules: SiO, H 2 O, SO, SO 2 ) stars, carbon-rich (C>O, HCN, HNC, CS, SiS, HC 3 N ) stars, S(O C) stars AGB stars: three classes of variability Mira variables (Miras, regular variables), SemiRegular variables (SR), irrerular variables *OH/IR stars: SED peaked at 6-10 µm with OH masers, 9.7 µm absorption features, and long periods of days, undetected at visual wavelengths Relatives of oxygen-rich AGB stars: supergiants (SG), post-agb stars SiO, H 2 O, OH maser emission from oxygen-rich AGB, SR, OH/IR, SG, post-agb etc. The supernova rate for our Galaxy: less than one in 30 years, whereas the rate of planetary nebulae is 1 per year or more 95-98%: low or intermediate mass stars and only 2-5%: high mass, of all stars dying

13 Schematic Overview of CSE of Oxygen-rich AGB Star (Decin et al. 2010) SiO Maser 22GHz H2O Maser OH Maser

14 Schematic View of Oxygen-rich AGB Stars AGB maser : Standard Model (Reid & Menten 1997) 22GHz H2O Maser eso.org Mira Variable Star Reid & Menten 1997

Introduction Studies of Late-Type Stars Mainly Based on Single Dish Stratification of masers in oxygen-rich AGB stars from three common molecules, SiO, H2O, OH different excitation conditions Good

15 Introduction Studies of Late-Type Stars Mainly Based on Single Dish Stratification of masers in oxygen-rich AGB stars from three common molecules, SiO, H2O, OH different excitation conditions Good probe for investigating physical condition & dynamics from inner CSE (atmosphere) to outer CSE SiO and H2O maser obs. until now: performed separately at different epochs using different tel. system : simultaneous obs. of 22/43/86/129 GHz bands Combined studies of SiO and 22 GHz H 2 O masers for spatial structure & kinematics and for dynamical evolution from AGB stars to post-agb/ppne : aspherical morphology, development of bipolarity, jets eso.org Herwig 2005, Ann Rev A&Ap

16 Single Dish Observations : Survey Overview of Single Dish Observations: Single Dish Survey toward ~1000 Evolved Stars at commissioning phase (22/43 GHz RXs) H 2 O (22 GHz ) SiO 28 v=1, J=1-0 (43 GHz) SRs, Miras, SGs etc. (401 known SiO and/or H2O maser sources) Both SiO and H2O maser detected sources (166) : Obs. in 2009 J. Kim & S.-H. Cho et al. (ApJS, 2010) SiO-only maser detected sources (83) : Obs. in S.-H. Cho & J. Kim (ApJ, 2012) H2O-only maser detected sources (152) : Obs. in J. Kim & S.-H. Cho et al. (AJ, 2013) Statistical studies J. Kim & S.-H. Cho et al. (AJ, 2014) OH/IR stars (252) : Obs. in 2012 Feb-June : C.-Y. Cho & S.-H. Cho et al. (ApJS, 2017) Post-AGB stars (182) +AGB (132) : Obs. in April D.-H. Yoon & S.-H. Cho et al. (ApJS, 2014) SiO 29 v=2, J=1-0 v=0, J=1-0

17 AGB star evolution in the IRAS two-color diagram Dashed line: Evolutionary track PN van der Veen & Habing (1988)

18 Simultaneous Obs. of SiO and H2O Masers toward Known Stellar SiO and H2O Maser Sources. I. (Kim & Cho et al. ApJS 2010) Summary Simultaneous obs. of both SiO and H2O masers toward 166 known SiO and H2O maser sources (SRs, Miras et al.) in 2009 June. Both SiO and H2O maser emission: detected from 112 sources (detection rate 67% in one epoch), SiO-only maser: from 42, H2O-only maser: from 4 sources. Most of the SiO masers appear around the stellar velocity, while H2O masers show different characteristics compared to SiO masers. There are more than 20 sources that show a one-way peak or double peaks with respect to the stellar velocity & SiO maser peak velocity. Average values of the H2O peak (integrated) intensity ratio with respect to SiO are 1.48 (0.83) in Mira variables, 2.20 (1.34) in OH/IR stars, 4.61 (8.91) in semi-regular variables. show increasingly larger values from Mira variables, OH/IR stars to semi-regular variables.

19 Sample Spectra

20 One-way, double Peaks of H2O Masers at Late Stage of AGB Evolution : Survey for 166 SRs, Miras (Kim & Cho et al. ApJS 2010) A large number of one-way, double peaks of H2O maser emission appear at later part of AGB star evolution in the IRAS two-color diagram (LI, RI: post-agb). No 45. QX Pup: PPN PPN One-way and double peaks of H2O may be associated with asymmetric outflows at later stage of AGB evolution need to confirm by interferometric obs. For 166 both SiO & H2O detected sources

Astrometric registration of the SiO & H2O masers toward QX Pup (OH231.8+4.2) : (Dodson et al.

21 Astrometric registration of the SiO & H2O masers toward QX Pup (OH ) : (Dodson et al accepted to MNRAS) Phase Referenced spot map of H2O, SiO v=1 and v=2 J=1-0 masers in OH on epoch Jan

22 Statistical studies Based on SD Survey Results of 401 Sources (Kim & Cho et al. AJ, 2014) Histogram of FWZP of SiO and H2O masers (Miras, OH/IR star) 13.7 km s km s km s km s -1 Logarithmic value of SiO v = 1, 2, J=1-0 (black circles, red circles) and H 2 O (green triangles) photon luminosities according to the optical phase Miras OH/IR Stars

23 Survey for 252 OH/IR Stars : SiO v=2-only Masers at Late Stage of AGB Evolution (Cho & Cho et al. ApJS 2017) A large number of SiO v=2-only masers were detected at later part of AGB star evolution of IRAS two-color diagram. For 252 OH/IR Stars IRAS Two-Color Diagram of 252 Observed OH/IR Stars (C.-Y. Cho MS thesis ) SiO v=2-only detection: related to its higher excitation temperature than v=1 and may occur due to thermalization of v = 1 maser. Intensity ratios of the v= 2 line to v = 1: determined by the shape of IR spectrum at 4 and 8 µm (Langer & Watson 1984) Development of hot dust shell from later stage of AGB evolution to post-agb? Similar results in post-agb survey (D.- H. Yoon et al. ApJS 2014)

24 Survey for Post-AGB Stars : Different Detection Rates between SiO and H 2 O Masers (Yoon & Cho et al. ApJS 2014) Different detection rates between SiO and H 2 O masers in RI and LI regions related with different abundances of masing molecules in stellar atmosphere according to different initial mass and expansion velocity. Two groups of post-agb stars (Sevenster 2002): LI (Left of IRAS, blue group; massive, higher outflow) and RI (Right of IRAS, red group) high abundances of Si molecule in massive, higher outflow region LI No. 28: IRAS No. 128: IRAS Nine Water fountain sources were monitored (J. Kim et al. in prep) SiO masers were not detected at any epochs: Density & abundance are not enough to detect SiO maser due to higher evolution No. 81: IRAS

25 VLBI Observations of Water Fountain Sources IRAS , Claussen et al HST F814W VLA VLBA

26 Summary of SD Survey Observations Both SiO and H 2 O masers are detected from a large number of AGB stars (SR, Mira, SG: 188/401, OH/IR: 50/252) at one-epoch obs. Both H 2 O & SiO masers are detected from known SiO-only and H 2 O-only detected sources. Intensity variation of SiO and H 2 O masers show similar patterns for several stars (Ref: H 2 O maser maximum are scattered in the range of phase, 0.7~1.5; Shintani et al. 2008). SiO maser intensities are stronger than H 2 O maser in most evolved stars and at most optical phases. However, peak intensities of H 2 O are stronger than those of SiO around maximum phases in several stars. FWZP of SiO maser shows a similar value in both Mira variables and OH/IR stars, while FWZP of H 2 O maser is large in OH/IR stars compared with that in Mira variables. One-way, double peaks of H 2 O masers, and SiO v=2-only masers appear at late stage of AGB evolution and at post-agb stage Different detection rates between SiO and H 2 O masers at post-agb stage

27 Single Dish Observations : Monitoring Selection of Monitoring Objects: Toward relatively strong SiO and/or H2O maser sources (~70) based on survey of 401 known SiO and/or H2O maser sources AGB (SRs, Miras, OH/IR) & SG stars (about 50 sources 16 VLBI KSP) * One-way peaks sources of H2O maser : NV Aur, V438 Sct (one/double) etc. * Double peaks or multiple H2O maser sources (about 20 sources) : WX Psc, BW Cam, V2108 Oph, V1366 Aql, NML Cyg, OH etc. S.-H. Cho, J. Kim & Y. Yun, JKAS, 2014 (TX Cam) Water fountain sources (9) : W43A, IRAS , IRAS etc. J. Kim et al. in prep. Post-AGB stars/ppn (5) : QX Pup, OH , OH etc. J. Kim, S.-H. Cho & D.-H. Yoon, JKAS, 2016 Symbiotic stars (6) : R Aqr, V407 Cyg, V627 Cas etc. S.-H. Cho, J. Kim & Y. Yun, JKAS, 2015 (V 407 Cas) Monitoring time intervals : Irregular 1-5 months at early stage, regular 2 months toward 16 KSP sources from 2015 Single dish studies and basic data for VLBI observations

28 Simultaneous Monitoring of SiO and H2O Masers VX Sgr (Yoon et al. in prep) Optical light curve Sample spectra of single dish P=732 days, D=1.57 kpc (Chen et al. 2007) Single dish radio intensity variations Preliminary results Mutual relation of SiO and H 2 O maser properties according to optical phases? - SiO intensities are stronger than H 2 O at most phases. - P.T(H 2 O)/P.T(SiO) shows maxima (larger than 1) around optical maximum phases. H 2 O intensities rapidly increase around optical max. compared to SiO intensities.

29 Monitoring of TX Cam: First Detection of 22 GHz H2O Masers (S.-H. Cho et al. JKAS 2014) The H2O detected epochs are shown in green.

Time Monitoring Observations : WF sources (Stellar H2O maser jets) W43 A H2O maser spectra obtained by the monitoring obs. from 2009 June to 2011 Dec. (J. Kim et al.

30 Time Monitoring Observations : WF sources (Stellar H2O maser jets) W43 A H2O maser spectra obtained by the monitoring obs. from 2009 June to 2011 Dec. (J. Kim et al. in prep) Red shifted components are strong until 2010 April, while blue-shifted components are not detected in 2010 March and stronger than redshifted ones from 2010 May to 2011 Dec. Asymmetric and discontinuous mass ejections in bipolar jet motions are clear.

31 MONITORING OBSERVATIONS OF H2O AND SiO MASERS TOWARD POST-AGB STARS (J. Kim et al. JKAS 2016) OH , OH Tracing the disappearing and weakening of H2O maser according to evolution at post-agb

32 Toward VLBI Key Science Project Based on SD Obs. Spatial structure and dynamical effect from SiO to 22 GHz H2O maser regions ( Maser movies) Pulsation and shock wave propagation effect via dust layer collaboration with mid-ir interferometry (VLTI/MIDI) Mutual association and difference between SiO and H 2 O masers Dynamical evolution from AGB to post-agb stars A large number of one-way, double peaks of H2O maser emission appear at later part of AGB star evolution (IRAS two-color diagram). Development process from AGB stars to Water fountain sources and their roles SiO masers were not detected at any epochs from 9 WFs Characteristics of SiO and H2O maser emission from AGB to post- AGB star evolution and at post-agb stage The different detection rates between SiO and H 2 O masers in RI and LI regions A large number of SiO v=2 only masers were detected at later part of AGB star evolution. Dynamical evolutionary scenario from AGB to post-agb stars Corresponding candidate objects for VLBI obs.

VLBI studies on the structure and dynamical effect of pulsation from SiO to H2O maser regions Case study: VLBA movie of SiO (v=1, J=1-0) toward TX Cam (Diamond & Kemball 2003) Imaged at biweekly

33 VLBI studies on the structure and dynamical effect of pulsation from SiO to H2O maser regions Case study: VLBA movie of SiO (v=1, J=1-0) toward TX Cam (Diamond & Kemball 2003) Imaged at biweekly intervals (121 epochs of data over 3 yrs: 2.5 pulsation periods) and animated movie at angular resolution 0.5 mas (+VERA): Synthesized movies of both SiO and H 2 O masers can be produced Expansion and contraction Spoke-like and jet motions Propagation of shock waves from SiO maser region to H 2 O region via dust formation layer

34 Supergiant Star VY CMa Results of 4 band SFPR obs.: SH Cho et al. in Prep VY CMa ( D) ( D) Optical light curve Sample spectrum of SD Six epoch data (red color) used for movies (6/29) Single dish radio intensity variations

35 Movies of H 2 O & SiO Masers (4 Bands): VY CMa All bands Q/W/D bands Proceedings of IAU 336 Symp. (Cho et al. 2017) Movies by YJ Yun We expect to trace the development of asymmetric outward motion from SiO to H 2 O maser regions in relation with stellar pulsation.

36 Movies of H 2 O & SiO Masers (4 Bands): IK Tau All bands Movies by YJ Yun : six epoch data were used Q/W/D bands Proceedings of IAU 336 Symp. (Cho et al. 2017)

37 Asymmetry starts from Mira variable stars Reid & Menten (2007) with VLA Semi-regular pulsating star: W Hya (P=361 days) VLA Cho et al. (2013 in Prep.) Radio photosphere SiO masers H 2 O masers Red filled circles: stellar size Green filled ellipses: radio continuum Contour and grey scale: SiO maser

Bipolar outflow (asymmetry) was triggered at a late stage of AGB winds Vinkovic et al.

38 Dynamical Evolution Studies from AGB to Post-AGB Stars/PPN Symmetry breaking in the evolution from AGB to planetary nebula? Bipolar outflow (asymmetry) was triggered at a late stage of AGB winds Vinkovic et al (WX Psc) Key Objects : water fountains? Precursor of water fountain? Candidate: WX Psc? OH/IR star: Bipolar outflow source of H 2 O maser (P=660 d.)

39 Long Period OH/IR Star WX Psc : YJ Yun et al. in Prep. Obs: Dec. 30, 2015 P= 660 days, D= ~650 pc SiO KaVA Image: YJ Yun et al. 2016

2002) W43A : H 2 O masers exist in a precessing jet Vlemmings et al.

40 Dynamical Evolution from AGB to Post-AGB Stars Key objects for breaking spherical symmetry : Water-fountain sources W43A with VLBA (Imai et al. 2002) W43A : H 2 O masers exist in a precessing jet Vlemmings et al The role of magnetic field is important! Pol. obs. (RCP&LCP) are required

41 Summary and Issues of 1 st Stage ES KSP Results (Proceedings IAU Symposium No. 336: Astrophysical Masers, Cho et al. 2017) We have obtained successful SFPR maps of H 2 O and SiO masers from 9 sources and focused on these 9 sources. Based on SFPR maps of H 2 O and SiO masers, we are investigating the spatial structure and kinematics from SiO to H 2 O maser regions: development of outward motion from ring-like/elliptical SiO to asymmetric 22 GHz H 2 O maser features. Asymmetric clumpy structure and the role of dust layer? SiO & H 2 O maser models coupled to hydrodynamical model of CSE Collaborations with Maser Theory & VLTI teams: M. Gray et al. (2009), Wittkowski et al. (2012) Different features of registered maps of H 2 O and SiO masers and different SiO maser features (ring-like, elliptical, irregular etc.) according to KSP sources Investigate the relation with characteristics of sources, evolutionary stage including the relation with light curve and pulsation mode (especially, in the case of different SiO maser features). Based on registered maps of SiO J=1-0, J=2-1 and J=3-2 masers The SiO maser distribution is different among SiO J=1-0, J=2-1, J=3-2 masers. Different dominant pumping mechanism according to different SiO transitions & sources? Please visit our home page KSP: url{

42 Maser Transitions at ALMA Frequency Range Perez-Sanchez & Vlemmings (2013)

16-19 using 16-20 antennas. (Beam: 0. 22 x 0.13 at 321 GHz, 0.11 x 0.06 at 659 GHz) Fig.

43 ALMA Sub-mm Maser and Dust Distribution of VY CMa Richards et al A&A Public Science Verification data for VY CMa observed on 2013 Aug using antennas. (Beam: x 0.13 at 321 GHz, 0.11 x 0.06 at 659 GHz) Fig. : Continuum emission: 321 GHz color scale, 658 GHz contours, two components C: continuum peak VY: the star at the center of water maser expansion

44 ALMA Sub-mm Maser and Dust Distribution of VY CMa Richards et al A&A H2O 325 GHz & Cont. H2O 658 GHz & Cont. H2O 321, 325, 658, 22 GHz

45 Summary (Richards et al. 2014) ALMA observations: identified the center of expansion of highexcitation masers with a distinct continuum peak, VY CMa itself (360 au NW of the brightest sub-mm dust emission). The 658-, 321- and 325-GHz masers are found at increasing distances from the star, but reach unexpectedly large separations. Some emission appears to emanate from shocked regions surrounding the star and tracing the limbs of C; interaction with the uniquely complex dust distribution. The velocities are generally consistent with expansion but deviate drastically and irregularly from spherical symmetry. These observations provide the first opportunity to test sub-mm maser models and pin down physical conditions in the dust formation zone, to be followed up in future papers along with analysis of the kinematics, thermal lines and dust.

Resolving the Stellar Activity of the Mira AB Binary with ALMA (Vlemmings et al. A&A 2015) Science verification data in Band 3 (Oct. 2014) and Band 6 (Nov.

46 Resolving the Stellar Activity of the Mira AB Binary with ALMA (Vlemmings et al. A&A 2015) Science verification data in Band 3 (Oct. 2014) and Band 6 (Nov. 2014) Fig: Mira AB binary at Band 6 (beam: 34x24 mas, left) For the first time the extended atmosphere of a star is resolved at these frequencies. For Mira A the diameter is AU in Band 3 (with brightness temperature Tb 5300 K) and AU in Band 6 (Tb 2500 K). A bright hotspot 0.4 AU and with Tb K is found on the stellar disc of Mira A. Resolving the extended atmosphere and the inner wind of Mira (o Ceti) with long ALMA baselines (K. T. Wong et al. A&A 2016) Band 6 Data GHz (1.3 mm) continuum SiOv = 0, 1, 2 J = SiO v = 0 J = 5 4 H2O ν2 = 1 J(Ka,Kc) = 5(5,0) 6(4,3)

Late-type Stars with Perspective of Radio Observations. Youngjoo Yun 2018 Radio Winter of Ulsan

Late-type Stars with Perspective of Radio Observations Youngjoo Yun 2018 Radio Winter School @University of Ulsan Outline l l l l Introduction to late-type stars with an example Brief description of stellar