Formation and dissolution of leaky clusters

TL;DR

This paper investigates the formation and evolution of leaky star clusters, proposing an inside-out star formation model with rapid gas expulsion leading to significant mass loss, based on observational data and numerical analysis.

Contribution

It introduces a detailed formation scenario for leaky clusters, emphasizing the role of gas expulsion and a specific density-radius relation over time.

Findings

Density-radius relation: rho ≈ 100*r^{-1.3} Msun pc^{-3}

Leaky clusters form sequentially with inside-out star formation

Rapid gas expulsion causes 80-90% mass loss within 20 Myr

Abstract

Massive Galactic clusters (> 1000 Msun) exhibit a clear correlation between cluster density, size and age and can be sorted in two categories, i.e. starburst and leaky clusters. The reason for the existance of two types of massive clusters is an open question. However, the answer is probably connected to a different formation histories of the two types. In this study we concentrate onleaky clusters only and investigate possible formation scenarios and gas expulsion phase. This is done by using existing observational data and numerical results of embedded cluster properties. Assuming that a clear correlation between cluster density, size and age exists, it is shown that the density-radius development over time forembedded clusters can be approximated by rho \approx 100*r ^{-1.3} Msun pc^{-3}. The consequences for the star formation process in leaky clusters are discussed and found to favour an inside-out star formation scenario with an initially low but later accelerated star formation rate. It is shown how the leaky clusters form in a unique sequential manner and that rapid gas expulsion is responsible for the 80-90\% mass loss over the next 20 Myr.