The Formation of Globular Clusters as a Case of Overcooling

TL;DR

This paper proposes that overcooling due to suppressed supernova feedback in massive stars leads to multiple star formation episodes in globular clusters, explaining their multiple populations.

Contribution

It introduces a novel model linking overcooling and binary star ejecta to the formation of multiple populations in globular clusters.

Findings

Massive binaries can produce chemical patterns of globular clusters.

Suppressed supernova feedback leads to runaway star formation.

Multiple star formation episodes are inevitable under these conditions.

Abstract

Driven by recent observational findings, we select massive interactive binaries as the most suitable among the existing candidates for producing the chemical patterns typical of multiple populations of Galactic globular clusters. Still, to avoid supernova contamination we are further driven to endorse the notion that above a critical mass stars fail to produce supernova events, but rather eventually sink into black holes without ejecting much energy and heavy metals. This assumption has the attractive implication of suppressing star formation feedback for some 5--10 million years, in practice leading to runaway star formation, analog to {\it overcooling} that in absence of feedback would have turned most baryons into stars in the early Universe. Under such conditions, multiple episodes of stars formation, incorporating binary star ejecta from previous episodes, appear to be unavoidable, thus accounting for the ubiquity of the multiple population phenomenon in globular clusters.