Dynamical mixing of two stellar populations in globular clusters

TL;DR

This paper investigates how the dynamical evolution of globular clusters, including gas expulsion and long-term processes, explains the observed ratio of chemically anomalous to standard stars, shedding light on their formation history.

Contribution

It demonstrates that both residual gas expulsion and long-term dynamical evolution are essential to reproduce the observed stellar population ratios in globular clusters.

Findings

Residual gas expulsion influences star ratios significantly.

Long-term evolution is necessary for the current population distribution.

Both processes together explain the observed chemical patterns.

Abstract

Stars in globular clusters (GCs) exhibit a peculiar chemical pattern with strong abundance variations in light elements along with a constant abundance in heavy elements. These abundance anomalies can be explained by a primordial pollution due to a first generation of fast rotating massive stars which released slow winds into the ISM from which a second generation of chemically anomalous stars can be formed. In particular the observed ratio of anomalous and standard stars in clusters can be used to constrain the dynamical evolution of GCs as around 95% of the standard stars need to be lost by the clusters. We show that both residual gas expulsion during the cluster formation and long term evolution are needed to achieve this ratio.