The effect of massive binaries on stellar populations and supernova progenitors

TL;DR

This study compares stellar population models with observations to understand the impact of massive binaries on stellar evolution and supernova progenitors, highlighting the need for additional mass loss mechanisms.

Contribution

It introduces updated binary and single star models and evaluates their consistency with observed stellar ratios and supernova rates.

Findings

Models agree with observations when combining single and binary stars.

Extra mass loss is needed to match the observed number of Wolf-Rayet stars.

Current models underpredict the number of red supergiants.

Abstract

We compare our latest single and binary stellar model results from the Cambridge STARS code to several sets of observations. We examine four stellar population ratios, the number of blue to red supergiants, the number of Wolf-Rayet stars to O supergiants, the number of red supergiants to Wolf-Rayet stars and the relative number of Wolf-Rayet subtypes, WC to WN stars. These four ratios provide a quantitative measure of nuclear burning lifetimes and the importance of mass loss during various stages of the stars' lifetimes. In addition we compare our models to the relative rate of type Ib/c to type II supernovae to measure the amount of mass lost over the entire lives of all stars. We find reasonable agreement between the observationally inferred values and our predicted values by mixing single and binary star populations. However there is evidence that extra mass loss is required to improve the agreement further, to reduce the number of red supergiants and increase the number of Wolf-Rayet stars.