Masses of subgiant stars from asteroseismology using the coupling strengths of mixed modes

TL;DR

This paper demonstrates that the coupling strength of mixed modes in subgiant stars, measured through asteroseismology, primarily depends on stellar mass and can improve mass estimations.

Contribution

It introduces a method to determine stellar masses from mixed mode coupling strength, independent of metallicity, enhancing asteroseismic analysis of subgiants.

Findings

Coupling strength correlates strongly with stellar mass.

Metallicity has negligible effect on coupling strength.

Method improves accuracy of stellar mass estimates.

Abstract

Since few decades, asteroseismology, the study of stellar oscillations, enables us to probe the interiors of stars with great precision. It allows stringent tests of stellar models and can provide accurate radii, masses and ages for individual stars. Of particular interest are the mixed modes that occur in subgiant solar-like stars since they can place very strong constraints on stellar ages. Here we measure the characteristics of the mixed modes, particularly the coupling strength, using a grid of stellar models for stars with masses between 0.9 and 1.5 M_{\odot}. We show that the coupling strength of the $\ell = 1$ mixed modes is predominantly a function of stellar mass and appears to be independent of metallicity. This should allow an accurate mass evaluation, further increasing the usefulness of mixed modes in subgiants as asteroseismic tools.