Prague Relativistic Astrophysics

Simone Recchi

Several ideas have been put forward in the recent past about the formation of globular clusters (GCs), but none of them seem to be fully satisfactory. In particular it is very challenging to explain the presence of multiple populations of stars and the anticorrelations between some light elements (in particular the Na/O and Mg/Al anticorrelations) within GC. For most of the proposed scenarios, in order to fit these anticorrelation the GC must lose a very large fraction of first generation stars, but it is unclear how to disperse such a huge fraction of stars. We propose here that first generation stars are formed in a supershell, swept up after the explosion of a very massive primordial star (the so-called popIII star). Since these supershell stars are born at some distance from the center of the GC, and since they inherit the outward-directed radial velocity of the supershell, it is likely that most of them will be unbound. On the other hand, a significant fraction of the ejecta of these supershell stars can propagate, almost unimpeded, towards the center of the GC. They pile up there, cool (because of the large densities reached in the center) and can form a new generation of stars. We will present in this seminar the details of this scenario and 1-D chemo-dynamical simulations corroborating it.