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

TL;DR

This study assesses how accurately asteroseismology can determine fundamental stellar parameters of exoplanet-host stars, highlighting the impact of method choice and mode number on uncertainties, which affects planetary radius estimates.

Contribution

It provides a detailed analysis of uncertainties in stellar parameters derived from asteroseismology, considering different comparison methods and mode counts, for the first time quantifying degeneracies and limits.

Findings

Uncertainties in stellar mass can reach up to 7%.

Luminosity uncertainties can exceed 10%.

Radius uncertainties are generally below 3%.

Abstract

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.} 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. 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.} 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.