Download Prospects for asteroseismology of solar

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
HeII
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
HD49933
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 (MultiMedia Service)
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)
HELAS VI: Helioseismology and applications
19
PLATO 2.0 targets
4300 deg2
(long stare fields)
For the
Baseline mission
20,000 deg2
(plus step
and stare
fields)
Noise Level
(ppm/√hr)
Number of
cool stars
mV
Number of
cool stars
34
22,000
9.8-11.3
85,000
267,000
11.6-12.9
1,000,000
(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, HeII 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