Sylvie VauclairLaboratoire d’Astrophysique de Toulouse-Tarbes, CNRS,Université de Toulouse, Institut universitaire de France

Precise Characterisation of Exoplanet-host Stars Parametersin connexion with the Formation and Evolution of Planetary Systems

IAU symposium 276, The Astrophysics of Planetary Systems, Torini October 11 to 15, 2010

Collaborations: Maria Eliana Escobar, Sylvie Théado, Noël Dolez, Gérard Vauclair and Corot team

• Asteroseismology of exoplanet-host stars: - determination of masses, radii, ages, luminosities, temperatures,evolutionary stages of the central stars- Rotation period and inclination of rotation axis

• Importance of chemical composition: metallicity and helium content,links with the theories for planets formation and migration, andaccretion on the central star (lithium tests)

SOPHIE OHP, T193August 2007

Asteroseismology :ground based and space

observations

Same instruments as for the detection of exoplanets

Ground: radial velocity methodsHARPS (La Silla), SOPHIE (OHP), AAT, VLT, Keck, etc…future: SONG

Space: photometric methodsMOST, COROT, KEPLER…

Four exoplanets-host stars observed on large periods (8 or 9 consecutive nights)

from the ground (solar-type stars all oscillate) :

mu Arae, HARPS 2004 iota Hor, HARPS 2006

51 Peg, SOPHIE 2007 and 201094 Cet, HARPS 2007

Arae (HARPS)

94 Ceti (HARPS)51 Peg (SOPHIE)

i Hor (HARPS)

Stochastic excitation of pressure waves.

Spherical harmonics:

is a Legendre polynomial

is a normalisation factor, so that the integral of

on the sphere is 1.

Basics of asterosismology(for slowly rotating stars) -1

Basics of asterosismology(for slowly rotating stars) -2

« asymptotic theory » (Tassoul 1980) :

Large separations : (n,l) = (n+1, l) – (n,l)

Small separations :

o

échelle diagram

iota Hor ->

<- mu Arae

1.06 Msun

1.20 Msun

1.15 Msun

1.10 Msun

L/L

sun

Soriano et al 2010 Arae

Y = 0.282

Evolutionary trackscomputed with the same metallicitybut different initial helium

(from Soriano and Vauclair, with TGEC)

The Y problem

1.14Msun

1.24Msun

1.20Msun1.28Msun

M/Mo = 1.25 +/- 0.01log g = 4.40 +/- 0.01Y = 0.255 +/- 0.015[Fe/H] = 0.16 +/- 0.03Age = 625 +/- 5 MyrR/Ro = 1.36+/- 0.01

M/Mo = 1.10+/- 0.01log g = 4.215+/- 0.01Y = 0.30+/- 0.01[Fe/H] = 0.30 +/- 0.03Age = 6.34+/- 0.4 GyrR/Ro = 1.84 +/- 0.01

Note: does not include uncertainties on physics: opacities, EOS, nuclear reactions rates, etc.

Arae Hor

Ages given in the literature (Saffe et al 2008)

Radial velocity curve during 9 nights and best planet-orbital fitting for 51 Peg (august 2010)

51 Peg1.06 Msun1.15 Rsun1.30 Lsun5665K8 Gyr

1 planetP=4.2j0.052 ua0.5 MJ

Single night radial velocity curve for 51 Peg.

Observational échelle diagram for 51 Peg. Comparison models: 1.1 M with [Fe/H]=0.20 and Y=0.3

Preliminary !

And one from space: HD52265CoRot main target, LRA2, 117 days

Ballot et al., in preparation

HD52265, CoRot main target, LF spectrum

Ballot et al., in preparation

Coralie : ESO/FEROS:Teff = 6076 +/- 57 Teff = 6131 +/- 47log g = 4.20 +/- 0.17 log g = 4.35 +/- 0.13 [Fe/H] = 0.20 +/- 0.07 [Fe/H] = 0.25 +/- 0.06

Mpsini = 1.09 MjPeriod : 119 dayse= 0.32; a = 0.5 AU

V = 6.2 , 35.6 mas Distance: 28 pcL/Lo = 1.94 +/- 0.16

HD52265 : COROT main target

LRA2, 117 days

HD52265 : COROT main target

LRA2, 117 days

42 modes p detected (l=0, 1, 2)Large separation 98.4 µHz ; small separation ~8.3 µHzrotation period: 11 daysinclination: 12°<i<37°1.8Mj<Mp<5.4Mj

log g = 4.285 +/- 0.01Teff = 6026L/Lo = 2.19age = 2.7 Gyrmass = 1.24

Importance of double-diffusive mixing(thermohaline)

initial diffusion-induced profile (just

before accretion)accretion-induced profile (just after the accretion event)-profile at 4 Myr-profile at 9 Myr-profile at 12 Myr

convective zone

radiative interior

Consequences ofaccretion-induced mixing:

See Poster

Sylvie Théado and Sylvie Vauclair

The stellar lithium as a tracer for intense planetesimal bombardment

Israelian et al, Nature 2010

Conclusions:

- Importance of asteroseismology for the determination of stellar parameters and inclination of rotation axis (~planetary plane ?)- Importance of the chemical composition and accretion processesin connexion with the scenarios of planetary formation and migration