Chemical evolution of star clusters

TL;DR

This paper reviews the chemical evolution of star clusters, especially old globular clusters, highlighting their unique formation conditions linked to the early Galaxy and discussing their potential origins in dark matter environments.

Contribution

It provides a detailed discussion on the formation and chemical evolution of globular clusters, emphasizing their distinct origins compared to younger clusters.

Findings

Globular clusters formed under unique early conditions.

Formation likely occurred within the proto-Galaxy or dark-matter minihaloes.

Different formation histories for halo and bulge clusters.

Abstract

I discuss the chemical evolution of star clusters, with emphasis on old globular clusters, in relation to their formation histories. Globular clusters clearly formed in a complex fashion, under markedly different conditions from any younger clusters presently known. Those special conditions must be linked to the early formation epoch of the Galaxy and must not have occurred since. While a link to the formation of globular clusters in dwarf galaxies has been suggested, present-day dwarf galaxies are not representative of the gravitational potential wells within which the globular clusters formed. Instead, a formation deep within the proto-Galaxy or within dark-matter minihaloes might be favoured. Not all globular clusters may have formed and evolved similarly. In particular, we may need to distinguish Galactic halo from Galactic bulge clusters.