A uniform asteroseismic analysis of 22 solar-type stars observed by Kepler

TL;DR

This study performs a uniform asteroseismic analysis of 22 bright solar-type stars observed by Kepler, demonstrating high-precision determinations of stellar properties and comparing different modeling approaches.

Contribution

It provides a systematic comparison of methods for deriving stellar parameters from asteroseismic data, highlighting the accuracy and consistency of individual frequency fitting.

Findings

Asteroseismic radii and masses are determined to ~1% precision.

Ages are estimated with ~2.5% precision.

Different modeling approaches show good agreement, with minor systematic differences.

Abstract

Asteroseismology with the Kepler space telescope is providing not only an improved characterization of exoplanets and their host stars, but also a new window on stellar structure and evolution for the large sample of solar-type stars in the field. We perform a uniform analysis of 22 of the brightest asteroseismic targets with the highest signal-to-noise ratio observed for 1 month each during the first year of the mission, and we quantify the precision and relative accuracy of asteroseismic determinations of the stellar radius, mass, and age that are possible using various methods. We present the properties of each star in the sample derived from an automated analysis of the individual oscillation frequencies and other observational constraints using the Asteroseismic Modeling Portal (AMP), and we compare them to the results of model-grid-based methods that fit the global oscillation properties. We find that fitting the individual frequencies typically yields asteroseismic radii and masses to \sim1% precision, and ages to \sim2.5% precision (respectively 2, 5, and 8 times better than fitting the global oscillation properties). The absolute level of agreement between the results from different approaches is also encouraging, with model-grid-based methods yielding slightly smaller estimates of the radius and mass and slightly older values for the stellar age relative to AMP, which computes a large number of dedicated models for each star. The sample of targets for which this type of analysis is possible will grow as longer data sets are obtained during the remainder of the mission.