Determining the helium abundance of stellar envelopes

Abstract

Intermediate-degree mode solar oscillation have been used to determine the solar helium abundance to a high degree of precision. However, we cannot expect to observe these modes in other stars. We investigate whether low degree modes that should be available from space-based asteroseismology missions can be used to determine the helium abundance with sufficient precision. We find that the oscillatory signal in the frequencies caused by the depression in Γ₁ in the second helium ionisation zone can be used to determine the envelope helium abundance of low mass stars.