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

Prospects for asteroseismology of solar-like stars

T. Appourchaux

Institut d’Astrophysique Spatiale, Orsay

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Contents

• What is a solar-like star?• A shopping list for physics• The store: PLATO 2.0• Summary

HELAS VI: Helioseismology and applications

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What is meant by a solar-like star?


Houdek et al (2000)

Huber (2014)

Huber et al (2011)

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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


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Rotation in solar-like stars


Nielsen et al (2014)

Davies et al (2014)

Seismically derived rotation provides light on differential rotation and gyrochronology

(a few stars)

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Rotation in evolved stars


Deheuvels et al (2014)

Subgiant stars having mixed modes provides the stellar rotation as a function of depth

(6 stars)

g-mode like

p-mode like

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Second differences: in depths...


Mazumdar et al (2014)

BCZ

HeII

Signatures and depths of the base of the convection and second Helium ionization zones(20 stars)

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...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)

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Mode physics: linewidth et al


Appourchaux et al (2014)

Different inferred background affects mode-physic parameters (and vice versa)

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Stellar linewidths



Linewidth depression at nmax decreases with effective temperature(23 stars)

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Stellar activity


Garcia et al (2010)

Garcia et al (2013)

Studies of stellar activity impact on seismic parameters to be done on more stars than just 2!

Sun HD49933

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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)

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Surface effects


Ball and Gizon (2014)

Understanding and proper modelling of surface effect key for stellar modelling(8 stars)

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Stellar mass and radius


Huber et al (2012)

White et al (2014)

Lebreton and Goupil (2014)

• Calibration of scaling laws using interferometry• From scaling laws to stellar modelling

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Stellar age


Lebreton and Goupil (2014)

Metcalfe et al (2012)

Age calibration possible on binary stars(3 binary stars)

Age determination on single stars(>50 stars)

No seismic proxy for stellar age (yet), model comparison required using

frequencies and /or ratio

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Binary stars


Chaplin et al (2014)

Seismic binary detection 0.5% for MS and subgiant stars to 1% for Red giants

A "typical" seismic binary (Kepler)


"Speckle-Interferometry" binary

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Clusters


Seismic scaling relation provides ways of

identifying cluster members

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)

Credits: G. Perez Diaz, IAC (MultiMedia Service)

PLATO 2.0

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PLATO 2.0 in short


- Selected by ESA in February 2014 - 32 « Normal » 12cm cameras, cadence 25 s, white light- 2 « Fast » 12cm cameras, cadence 2.5 s, 2 colours- Dynamic range: 4 ≤ mV ≤ 16- L2 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)

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PLATO 2.0 targets


4300 deg2 (long stare fields)

20,000 deg2 (plus step and stare

fields)

Noise Level (ppm/√hr)

Number of cool stars

mV Number of cool stars

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(Asteroseismology)

22,000 9.8-11.3 85,000

80(Earth radius detection)

267,000 11.6-12.9 1,000,000

For the Baseline mission

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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, HeII zone– Stellar activity– Seismic inversion and diagnostics (left out here...)

• Stellar physics will be calibrated with:– Binary stars and clusters


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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)

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

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