On the origin of complex stellar populations in star clusters

TL;DR

This paper explores how complex stellar populations in star clusters can form through mechanisms like star capture and gas accretion, challenging traditional star formation models.

Contribution

It introduces the idea that star clusters can acquire older stars and restart star formation by accreting gas, explaining observed population complexities.

Findings

Star clusters can capture field stars during formation.

Massive globular clusters can accrete gas and restart star formation.

These processes explain the presence of multiple stellar populations.

Abstract

The existence of complex stellar populations in some star clusters challenges the understanding of star formation. E.g. the ONC or the sigma Orionis cluster host much older stars than the main bulk of the young stars. Massive star clusters (omega Cen, G1, M54) show metallicity spreads corresponding to different stellar populations with large age gaps. We show that (i) during star cluster formation field stars can be captured and (ii) very massive globular clusters can accrete gas from a long-term embedding inter stellar medium and restart star formation.