To be published in:
Astronomy & Astrophysics
The self-enrichment of galactic halo globular clusters: a clue to
their formation ?
C. Neuforge1 ,
A. Noels1 and
1 Institut d'Astrophysique et de Géophysique - Université de Liège, Avenue de Cointe 5, 4000 Liège, Belgium
* Maître de Recherches FNRS, Belgium
** Chercheur Qualifié FNRS, Belgium
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
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.
globular clusters: general - Galaxy: evolution -
supernovæ: general - ISM: bubbles - population III
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