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Sylvie Vauclair Laboratoire d’Astrophysique de Toulouse-Tarbes, CNRS,

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  1. Precise Characterisation of Exoplanet-host Stars Parameters in connexion with the Formation and Evolution of Planetary Systems Sylvie Vauclair Laboratoire d’Astrophysique de Toulouse-Tarbes, CNRS, Université de Toulouse, Institut universitaire de France Collaborations: Maria Eliana Escobar, Sylvie Théado, Noël Dolez, Gérard Vauclair and Corot team IAU symposium 276, The Astrophysics of Planetary Systems, Torini October 11 to 15, 2010

  2. 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, and • accretion on the central star (lithium tests) SOPHIE OHP, T193 August 2007

  3. Asteroseismology :ground based and space observations Same instruments as for the detection of exoplanets Ground: radial velocity methods HARPS (La Silla), SOPHIE (OHP), AAT, VLT, Keck, etc…future: SONG Space: photometric methods MOST, COROT, KEPLER…

  4. Four exoplanets-host stars observed on large periods (8 or 9 consecutive nights) from the ground (solar-type stars all oscillate) : iota Hor, HARPS 2006 mu Arae, HARPS 2004 51 Peg, SOPHIE 2007 and 2010 94 Cet, HARPS 2007

  5. i Hor (HARPS)  Arae (HARPS) 94 Ceti (HARPS) 51 Peg (SOPHIE)

  6. Basics of asterosismology(for slowly rotating stars) -1 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.

  7. Basics of asterosismology(for slowly rotating stars) -2 « asymptotic theory » (Tassoul 1980) : Large separations : Dn (n,l) = n (n+1, l) – n (n,l) Small separations : o échelle diagram

  8. <- mu Arae iota Hor ->

  9. 1.10 Msun 1.15 Msun Soriano et al 2010 m Arae 1.20 Msun 1.06 Msun L/Lsun

  10. The Y problem Y = 0.282 1.24Msun 1.14Msun Evolutionary tracks computed with the same metallicity but different initial helium (from Soriano and Vauclair, with TGEC) 1.28Msun 1.20Msun

  11. m Arae i Hor M/Mo = 1.10+/- 0.01 log g = 4.215+/- 0.01 Y = 0.30+/- 0.01 [Fe/H] = 0.30 +/- 0.03 Age = 6.34+/- 0.4 Gyr R/Ro = 1.84 +/- 0.01 M/Mo = 1.25 +/- 0.01 log g = 4.40 +/- 0.01 Y = 0.255 +/- 0.015 [Fe/H] = 0.16 +/- 0.03 Age = 625 +/- 5 Myr R/Ro = 1.36+/- 0.01 Note: does not include uncertainties on physics: opacities, EOS, nuclear reactions rates, etc.

  12. Ages given in the literature (Saffe et al 2008)

  13. 51 Peg 1.06 Msun 1.15 Rsun 1.30 Lsun 5665K 8 Gyr 1 planet P=4.2j 0.052 ua 0.5 MJ Radial velocity curve during 9 nights and best planet-orbital fitting for 51 Peg (august 2010)

  14. Single night radial velocity curve for 51 Peg.

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

  16. And one from space: HD52265 CoRot main target, LRA2, 117 days Ballot et al., in preparation

  17. HD52265, CoRot main target, LF spectrum Ballot et al., in preparation

  18. HD52265 : COROT main target LRA2, 117 days V = 6.2 , p = 35.6 mas Distance: 28 pc L/Lo = 1.94 +/- 0.16 Mpsini = 1.09 Mj Period : 119 days e= 0.32; a = 0.5 AU Coralie : ESO/FEROS: Teff = 6076 +/- 57 Teff = 6131 +/- 47 log g = 4.20 +/- 0.17 log g = 4.35 +/- 0.13 [Fe/H] = 0.20 +/- 0.07 [Fe/H] = 0.25 +/- 0.06

  19. HD52265 : COROT main target LRA2, 117 days 42 modes p detected (l=0, 1, 2) Large separation 98.4 µHz ; small separation ~8.3 µHz rotation period: 11 days inclination: 12°<i<37° 1.8Mj<Mp<5.4Mj log g = 4.285 +/- 0.01 Teff = 6026 L/Lo = 2.19 age = 2.7 Gyr mass = 1.24

  20. Importance of double-diffusive mixing (thermohaline)

  21. Consequences of accretion-inducedmixing: See Poster Sylvie Théado and Sylvie Vauclair The stellar lithium as a tracer for intense planetesimalbombardment radiative interior convective zone 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

  22. Israelian et al, Nature 2010

  23. Conclusions: - Importance of asteroseismology for the determination of stellar parameters and inclination of rotation axis (~planetary plane ?) - Importance of the chemical composition and accretion processes in connexion with the scenarios of planetary formation and migration