Impact of metallicity on the evolution of young star clusters

TL;DR

This study uses N-body simulations to explore how metallicity affects the dynamical evolution of young star clusters, revealing that metal-poor clusters expand faster and have larger half-light radii due to reduced stellar wind mass loss.

Contribution

It provides the first detailed analysis of metallicity's impact on young star cluster evolution using metallicity-dependent stellar evolution models.

Findings

Metal-poor clusters experience less mass loss from stellar winds.

Core re-expansion after collapse is weaker in metal-poor clusters.

Metallicity significantly affects the half-light radius expansion.

Abstract

We discuss the results of N-body simulations of intermediate-mass young star clusters (SCs) with three different metallicities (Z=0.01, 0.1 and 1 Zsun), including metallicity-dependent stellar evolution recipes and metallicity-dependent prescriptions for stellar winds and remnant formation. The initial half-mass relaxation time of the simulated young SCs (~10 Myr) is comparable to the lifetime of massive stars. We show that mass-loss by stellar winds influences the reversal of core collapse and the expansion of the half-mass radius. In particular, the post-collapse re-expansion of the core is weaker for metal-poor SCs than for metal-rich SCs, because the former lose less mass (through stellar winds) than the latter. As a consequence, the half-mass radius expands faster in metal-poor SCs. The difference in the half-light radius between metal-poor SCs and metal-rich SCs is (up to a factor of two) larger than the difference in the half-mass radius.