PROBING STELLAR DYNAMICS WITH SPACE PHOTOMETRY RESULTS FROM COROT - - PowerPoint PPT Presentation

probing stellar dynamics with space photometry
SMART_READER_LITE
LIVE PREVIEW

PROBING STELLAR DYNAMICS WITH SPACE PHOTOMETRY RESULTS FROM COROT - - PowerPoint PPT Presentation

PROBING STELLAR DYNAMICS WITH SPACE PHOTOMETRY RESULTS FROM COROT AND KEPLER Rafael A. Garca Service dAstrophysique, CEA-Saclay, France Special thanks to: J. Ballot, P.G. Beck, O. Benomar, A. Bonanno, A.S. Brun, M. Cantiello, T. Ceillier,


slide-1
SLIDE 1

1

PROBING STELLAR DYNAMICS WITH SPACE PHOTOMETRY

RESULTS FROM COROT AND KEPLER Rafael A. García

Service d’Astrophysique, CEA-Saclay, France

Special thanks to:

  • J. Ballot, P.G. Beck, O. Benomar, A. Bonanno, A.S. Brun, M. Cantiello, T. Ceillier, G.R. Davies, S. Deheuvels, R. Egeland, A.

Lanza, S. Mathur, T. Metcalfe, J. Do Nascimiento, and D. Salabert

slide-2
SLIDE 2

I-INTRODUCTION

2

Ø What can offer high-precision photometry (HPP) to better understand stellar dynamics, magnetism & dynamos ?

§ HPP observations can potentially give access to:

  • Surface (differential?) rotation of hundred to thousand stars
  • Internal (differential?) rotation through seismology

§ Convection properties

  • Characteristic time scale of convection (granulation)

§

  • ther scales:
  • e.g. Faculae in active stars

§ Internal structure (through seismology)

  • Size of the convective envelope (through seismology (+ modelling))
  • Constraining deep internal magnetic fields & convective core dynamos

§ Activity cycles & surface magnetism

  • Through the analysis of long time series (activity proxies)

§ Or asteroseismology

[e.g. Beck et al. 2012; Deheuvels et al. 2012,2014,2015; Mosser et al. 2012, Nielsen et al. 2014, Benomar et al. 2016, Pia di Mauro et al. 2016, [e.g. Karoff et al. 2013] [e.g. McQuillan et al. 2013, 2014; Nielsen et al. 2013; Reinhold & Reiners 2013, 2015; García et al. 2014] [e.g. Mathur et al. 2011; Kallinger et al. 2014, 2016] [e.g. Mathur et al. 2012; Mazumdar et al. 2014; Metcalfe et al. 2014,…] [e.g. García et al. 2010; Mathur et al. 2013, 2014, Salabert et al. 2016] [e.g. García et al. 2010; Régulo et al. submitted] [Fuller et al. 2015.; Stello et al. 2016a,b]

slide-3
SLIDE 3

3

IIa-Stellar Dynamics: Surface Rotation

slide-4
SLIDE 4

II-SURFACE ROTATION

4

[McQuillan et al. 2014]

slide-5
SLIDE 5

II-SURFACE ROTATION (M-S & SUB-RG)

5

Ø ~540 solar-like stars showing p-mode oscillations have been measured (1 month)

§ Reliable surface rotation rates and photospheric magnetic index obtained for 310 stars

Ø Stars in which pulsations are measured => Low surface activity (biased sample)

[Chaplin et al. 2014] [García et al 2014] [Garcia et al. 2010; Chaplin et al. 2011]

slide-6
SLIDE 6

II-SURFACE ROTATION OF (SEISMIC) KOIS

6

[see also Angus et al. 2015, Paz-Chinchón et al. 2015, Van Saders et al. 2016]

Ø Gyrochronology

§ must be calibrated using stars of known age (published relations mostly employ open cluster stars and the Sun). § Until now, gyrochronology has simply extrapolated these trends to stars older than the Sun.

Ø Using also confirmed stars holding planets

§ Small planets in the range 0.7 to 3.94 R with semi-major axes range from 0.035 to 0.392 AU § Differences are due to a difference mass distribution Field stars (García et al. 2014) Stars harbouring planets (Ceillier et al. 2016)

[See Van Saders presentation tomorrow]

slide-7
SLIDE 7

II-SURFACE ROTATION (RGB-RC)

7

[Ceillier, Tayar, et al. to be submitted]

Ø Ensemble analysis of 17,000 Kepler pulsating RGs

§ ~361 shows reliable surface rotation (blue) § 171 that could be due to pollution (grey)

Ø As expected

§ Most are RC stars § Some possible mergers detected

Average rotation splitting measured for ~300 RG stars

slide-8
SLIDE 8

8

III-Stellar Dynamics: Surface magnetism

slide-9
SLIDE 9

III-STELLAR VARIABILITY

9

Ø Example of the PSD of a Solar-Like star

Photon noise

Granulation

slide-10
SLIDE 10

II-MAGNETIC ACTIVITY & ROTATION

VIRGO/SPM

[García, Salabert, Mathur et al. 2013]

slide-11
SLIDE 11

II-MAGNETIC ACTIVITY & ROTATION

[Salabert et al. in preparation]

slide-12
SLIDE 12

III-SURFACE MAGNETIC ACTIVITY S-L STARS

12

Ø The photospheric magnetic activity of the pulsating solar-like stars

§ Compatible with the solar magnetic activity during the solar cycle (61.5%) § But large range of inclination angles and position in an on-going long activity cycle

[García et al. 2014]

slide-13
SLIDE 13

III-SURFACE MAGNETIC ACTIVITY S-L STARS

13

Ø Analysis of 18 seismic solar analogues observed by Kepler

§ Solar analogs in Teff and Mass [see also Do Nascimento et al. 2014]

  • Degeneracy because of the unknown inclination axis and period of the cycle.

§ The surface magnetic activity of the pulsating solar analogues is similar to the Sun

[Salabert et al., accepted, minor revision ] [For the variability of KOIs see: McQuillan et al. 2013; Walkowicz & Basri 2013] global oscillation & photometry global oscillation & spectroscopy

  • ne-month individual frequencies & spectroscopy

nine-month individual frequencies & spectroscopy

slide-14
SLIDE 14

III-SURFACE MAGNETIC ACTIVITY S-L STARS

14

Ø Analysis of 18 seismic solar analogs observe by Kepler

§ Solar analogs in Teff and Mass [see also Do Nascimento et al. 2014]

  • Degeneracy because of the unknown inclination axis and period of the cycle.

§ The surface magnetic activity of the pulsating solar analogues is similar to the Sun

[Salabert et al., accepted, minor revision ] [For the variability of KOIs see: McQuillan et al. 2013; Walkowicz & Basri 2013]

MWO Solar Analogues Kepler Solar Analogues

slide-15
SLIDE 15

HINTS OF A MAGNETIC-ACTIVITY CYCLE

15

Ø KIC 10644253: a Solar analogue

§ Correlation between Sph and p-mode frequency shifts

Kepler

[Salabert et al. 2016] Teff=6030±150 M=1.13±0.05 R=1.108±0.016 Age=1.07±0.25Gy Prot~ 11 days I ~ 48o [Bruntt et al. 2012; Metcalfe et al. 2014; García et al. 2014,Salabert et al. 2016]

l=0, l=1

slide-16
SLIDE 16

HINTS OF A MAGNETIC-ACTIVITY CYCLE

16

Ø KIC 10644253: a Solar analogue

§ Correlation between Sph and p-mode frequency shifts

Kepler

[Salabert et al. 2016] Teff=6030±150 M=1.13±0.05 R=1.108±0.016 Age=1.07±0.25Gy Prot~ 11 days I ~ 48o [Bruntt et al. 2012; Metcalfe et al. 2014; García et al. 2014,Salabert et al. 2016]

l=0, l=1

Ca H&K

[Salabert et al., accepted, minor revision ]

slide-17
SLIDE 17

17

Thanks