Asteroseismology of exoplanets hosts stars : tests of internal metallicity

Abstract

Exoplanets host stars present a clear metallicity excess compared to stars without detected planets, with an average overabundance of 0.2 dex. This excess may be primordial, in which case the stars should be overmetallic down to their center, or it may be due to accretion in the early phases of planetary formation, in which case the stars would be overmetallic only in their outer layers. In the present paper, we show the differences in the internal structure of stars, according to the chosen scenario. Namely two stars with the same observable parameters (luminosity, effective temperature, outer chemical composition) are completely different in their interiors according to their past histories, which we reconstitute through the computations of their evolutionary tracks. It may happen that stars with an initial overmetallicity have a convective core while the stars which suffered accretion do not. We claim that asteroseismic studies of these exoplanets host stars can give clues about their internal structures and metallicities, which may help in understanding planetary formation.

24 pages, 18 figures, accepted by A&A

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• The Chemical Compositions of Stars with Planets: A Review
• The exoplanet-host star iota Horologii: an evaporated member of the primordial Hyades cluster
• Seismic analysis of the second ionization region of helium in the Sun: I. Sensitivity study and methodology
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• Lithium abundances in exoplanet-host stars : modelling
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• The CoRoT primary target HD 52265: models and seismic tests
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• Observational techniques to measure solar and stellar oscillations
• A Possible Stellar Metallic Enhancement in Post-T Tauri Stars by a Planetesimal Bombardment
• Current Issues in Asteroseismology