Mass loss of stars in star clusters: an energy source for dynamical evolution

TL;DR

This paper demonstrates that in dense star clusters with short relaxation times, stellar mass loss in the core provides the energy driving their dynamical expansion, balancing energy transport via two-body relaxation.

Contribution

It reveals that stellar mass loss acts as a key energy source for cluster expansion, especially in clusters with rapid relaxation times, linking stellar evolution to dynamical evolution.

Findings

Mass loss from stars in the core drives cluster expansion.

Expansion occurs on the relaxation time scale for clusters with short initial relaxation times.

Stellar mass loss energy balances the energy transported outward by relaxation.

Abstract

Dense star clusters expand until their sizes are limited by the tidal field of their host galaxy. During this expansion phase the member stars evolve and lose mass. We show that for clusters with short initial relaxation time scales (<~100 Myr) the dynamical expansion is largely powered by mass loss from stars in the core, but happens on a relaxation time scale. That is, the energy release following stellar mass loss is in balance with the amount of energy that is transported outward by two-body relaxation.