Constraining the evolution of red supergiants with the integrated light of star clusters

TL;DR

This paper explores how stochastic variations in red supergiants affect the integrated light of young star clusters and discusses methods to account for these fluctuations to better constrain stellar evolution models.

Contribution

It introduces Bayesian approaches and discusses prospects for modeling stochastic effects of red supergiants in unresolved star clusters.

Findings

Red supergiants cause significant variability in cluster light.

Bayesian methods can help constrain stellar evolution models.

Open issues remain in modeling stochastic fluctuations.

Abstract

The integrated properties of young star clusters are subject to large cluster-to-cluster variations because they depend directly on small numbers of bright stars. At ages at which red supergiants are expected to exist, these luminous but rare stars can be blamed for most of the variations. If unresolved clusters are to be used to constrain red supergiant models, methods must be developed that take these stochastic fluctuations into account. We discuss prospects and open issues in this field, based on recent work on high mass clusters in M82, and on first experiments towards a Bayesian study of cluster populations.