Accuracy of stellar parameters of exoplanet-host stars determined from asteroseismology

¹ C.R.A.L, CNRS, UMR5574 École normale supérieure, 46 allée d'Italie, 69007 Lyon, France e-mail: [cedric.mulet-marquis;ibaraffe]@ens-lyon.fr
² School of Physics, University of Exeter, Stocker Road, Exeter, EX4 4QL, UK e-mail: [suz;fpont]@astro.ex.ac.uk

Received: 20 February 2009
Accepted: 16 June 2009

Abstract

Context. In the context of the space-based mission CoRoT, devoted to asteroseismology and search for planet transits, we analyse the accuracy of fundamental stellar parameters (mass, radius, luminosity) that can be obtained from asteroseismological data.

Aims. Our work is motivated by the large uncertainties on planetary radius determination of transiting planets which are mainly due to uncertainties on the stellar parameters. Our goal is to analyse uncertainties of fundamental stellar parameters for a given accuracy of oscillation frequency determination.

Methods. We generate grids of equilibrium models of stars and compute their pulsation spectra based on a linear nonadiabatic stability analysis. Using differents methods of comparison of oscillation mode spectra, we derive uncertainties on fundamental stellar parameters and analyse the effect of varying the number of considered modes.

Results. The limits obtained depend strongly on the adapted method to compare spectra. We find a degeneracy in the stellar parameter solutions, up to a few % in mass (from less than 1% to more than 7% depending on the method used and the number of considered modes), luminosity (from 2% to more than 10%) or radius (from less than 1% to 3%), for a given pulsation spectrum.