We present a model of globular cluster self-enrichment. In the protogalaxy,
cold and dense clouds embedded in the hot protogalactic medium are assumed to
be the progenitors of galactic halo globular clusters. The massive stars of a
first generation of metal-free stars, born in the central areas of the
proto-globular cluster clouds, explode as Type II supernovae. The associated
blast waves trigger the expansion of a supershell, sweeping all the material of
the cloud, and the heavy elements released by these massive stars enrich the
supershell. A second generation of stars is born in these compressed and
enriched layers of gas. These stars can recollapse and form a globular cluster.
This work aims at revising the most often encountered argument against
self-enrichment, namely the presumed ability of a small number of supernovae to
disrupt a proto-globular cluster cloud. We describe a model of the dynamics of
the supershell and of its progressive chemical enrichment. We show that the
minimal mass of the primordial cluster cloud required to avoid disruption by
several tens of Type II supernovae is compatible with the masses usually
assumed for proto-globular cluster clouds. Furthermore, the corresponding
self-enrichment level is in agreement with halo globular cluster metallicities.Comment: 12 pages, 7 figures. Accepted for publication in Astronomy and
Astrophysic
