Prospects for asteroseismology of solarlike stars T Appourchaux

Prospects for asteroseismology of solar-like stars T. Appourchaux Institut d’Astrophysique Spatiale, Orsay

Contents • • HELAS VI: Helioseismology and applications What is a solar-like star? A shopping list for physics The store: PLATO 2. 0 Summary 2

What is meant by a solar-like star? Huber (2014) Huber et al (2011) Houdek et al (2000) HELAS VI: Helioseismology and applications 3

Shopping list for physics • • Internal rotation (Subgiant stars, MS star) Helium ionization and convection zones Excitation and damping (mode physics) Stellar cycle and activity Atmosphere: surface effect, asymmetries Stellar Radius, Mass and Age Clusters and Binary stars HELAS VI: Helioseismology and applications 4

Rotation in solar-like stars Nielsen et al (2014) Seismically derived rotation provides light on differential rotation and gyrochronology (a few stars) HELAS VI: Helioseismology and applications Davies et al (2014) 5

Rotation in evolved stars Deheuvels et al (2014) g-mode like p-mode like Subgiant stars having mixed modes provides the stellar rotation as a function of depth (6 stars) HELAS VI: Helioseismology and applications 6

Second differences: in depths. . . Mazumdar et al (2014) BCZ He. II Signatures and depths of the base of the convection and second Helium ionization zones (20 stars) HELAS VI: Helioseismology and applications 7

. . . leading to Helium abundance Verma et al (2014) Amplitude of the signature of the second Helium ionization zone as a marker of helium abundance (1 star) HELAS VI: Helioseismology and applications 8

Mode physics: linewidth et al Appourchaux et al (2014) Different inferred background affects mode-physic parameters (and vice versa) HELAS VI: Helioseismology and applications 9

Stellar linewidths Appourchaux et al (2014) Linewidth depression at nmax decreases with effective temperature (23 stars) HELAS VI: Helioseismology and applications 10

Stellar activity Garcia et al (2013) Garcia et al (2010) Sun HD 49933 Studies of stellar activity impact on seismic parameters to be done on more stars than just 2! HELAS VI: Helioseismology and applications 11

Departure from Lorentzian mode profile (asymmetry) Toutain and Kosovichev (2005) Mode asymmetry yet to be detected in other stars than the Sun (impact on stellar modelling) HELAS VI: Helioseismology and applications 12

Surface effects Ball and Gizon (2014) Understanding and proper modelling of surface effect key for stellar modelling (8 stars) HELAS VI: Helioseismology and applications 13

Stellar mass and radius Huber et al (2012) • Calibration of scaling laws using interferometry • From scaling laws to stellar modelling Lebreton and Goupil (2014) White et al (2014) HELAS VI: Helioseismology and applications 14

Stellar age Lebreton and Goupil (2014) No seismic proxy for stellar age (yet), model comparison required using frequencies and /or ratio Metcalfe et al (2012) Age determination on single stars (>50 stars) HELAS VI: Helioseismology and applications Age calibration possible on binary stars (3 binary stars) 15

Binary stars A "typical" seismic binary (Kepler) "Speckle-Interferometry" binary Chaplin et al (2014) Appourchaux et al (2012) Seismic binary detection 0. 5% for MS and subgiant stars to 1% for Red giants HELAS VI: Helioseismology and applications 16

Clusters Appourchaux et al (1993) Stello et al (2011) Improved stellar age precision and other stellar parameters with cluster by a factor 3 (No cluster MS stars but. . . cluster RG stars) HELAS VI: Helioseismology and applications Seismic scaling relation provides ways of identifying cluster members 17

PLATO 2. 0 Credits: G. Perez Diaz, IAC (Multi. Media Service)

PLATO 2. 0 in short - Selected by ESA in February 2014 - 32 « Normal » 12 cm cameras, cadence 25 s, white light - 2 « Fast » 12 cm cameras, cadence 2. 5 s, 2 colours - Dynamic range: 4 ≤ m. V ≤ 16 - L 2 orbit - Nominal mission duration: 6 years launched in 2024 - 2 long pointings of 2 -3 years + step-and-stare phase (2 -5 months per pointing) HELAS VI: Helioseismology and applications 19

PLATO 2. 0 targets 4300 deg 2 (long stare fields) For the Baseline mission 20, 000 deg 2 (plus step and stare fields) Noise Level (ppm/√hr) Number of cool stars m. V Number of cool stars 34 22, 000 9. 8 -11. 3 85, 000 267, 000 11. 6 -12. 9 1, 000 (Asteroseismology) 80 (Earth radius detection) HELAS VI: Helioseismology and applications 20

Summary • Stellar physics will face a revolution with PLATO 2. 0 • Stellar physics will improve in the following fields: – Stellar evolution – Internal structure and rotation (g modes? ) – Convection zone, He. II zone – Stellar activity – Seismic inversion and diagnostics (left out here. . . ) • Stellar physics will be calibrated with: – Binary stars and clusters HELAS VI: Helioseismology and applications 21

PLATO 2. 0 observing strategy Baseline observing strategy: • 6 years nominal science operation • 2 long pointings of 2 -3 years + step-and-stare phase (2 -5 months per pointing) HELAS VI: Helioseismology and applications 22