Verification of the Kepler Input Catalog from Asteroseismology of Solar-type Stars

TL;DR

This study uses asteroseismology to verify stellar properties in the Kepler Input Catalog, revealing biases in surface gravity and radius estimates that impact exoplanet characterization.

Contribution

It provides the first large-scale comparison between asteroseismic and catalog stellar parameters, identifying systematic biases in the KIC.

Findings

KIC overestimates log(g) by 0.23 dex for certain stars.

KIC underestimates stellar radii by up to 50% for stars with R < 2 R_sun.

Potential underestimation of exoplanet sizes based on KIC radii.

Abstract

We calculate precise stellar radii and surface gravities from the asteroseismic analysis of over 500 solar-type pulsating stars observed by the Kepler space telescope. These physical stellar properties are compared with those given in the Kepler Input Catalog (KIC), determined from ground-based multi-color photometry. For the stars in our sample, we find general agreement but we detect an average overestimation bias of 0.23 dex in the KIC determination of log (g) for stars with log (g)_KIC > 4.0 dex, and a resultant underestimation bias of up to 50% in the KIC radii estimates for stars with R_KIC < 2 R sun. Part of the difference may arise from selection bias in the asteroseismic sample; nevertheless, this result implies there may be fewer stars characterized in the KIC with R ~ 1 R sun than is suggested by the physical properties in the KIC. Furthermore, if the radius estimates are taken from the KIC for these affected stars and then used to calculate the size of transiting planets, a similar underestimation bias may be applied to the planetary radii.