Asteroseismic estimate of helium abundance of a solar analog binary system

TL;DR

This study uses Kepler data to analyze solar-like oscillations in 16 Cyg A and B, estimating their helium abundance by calibrating the signatures of the helium ionization zone on their oscillation frequencies.

Contribution

It provides the first direct asteroseismic estimates of helium abundance for these solar analogs using their oscillation frequency signatures.

Findings

Helium abundance of 16 Cyg A is between 0.231 and 0.251.

Helium abundance of 16 Cyg B is between 0.218 and 0.266.

The method calibrates helium ionization signatures against models to determine stellar helium content.

Abstract

16 Cyg A and B are among the brightest stars observed by Kepler. What makes these stars more interesting is that they are solar analogs. 16 Cyg A and B exhibit solar-like oscillations. In this work we use oscillation frequencies obtained using 2.5 years of Kepler data to determine the current helium abundance of these stars. For this we use the fact that the helium ionization zone leaves a signature on the oscillation frequencies and that this signature can be calibrated to determine the helium abundance of that layer. By calibrating the signature of the helium ionization zone against models of known helium abundance, the helium abundance in the envelope of 16 Cyg A is found to lie in the range 0.231 to 0.251 and that of 16 Cyg B lies in the range 0.218 to 0.266.