Asteroseismic estimate of helium abundance of a solar analog binary system

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.

Accepted for publication in ApJ

References in corpus (8)

• Modules for Experiments in Stellar Astrophysics (MESA)
• The Dartmouth Stellar Evolution Database
• Correcting stellar oscillation frequencies for near-surface effects
• YREC: The Yale Rotating Stellar Evolution Code
• Asteroseismology of the solar analogs 16 Cyg A & B from Kepler observations
• A precise asteroseismic age and radius for the evolved Sun-like star KIC 11026764
• An asteroseismic signature of helium ionization
• On the opacity change required to compensate for the revised solar composition

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