On the origin of the helium-rich population in Omega Centauri
  To study the possible origin of the huge helium enrichment attributed to the
stars on the blue main sequence of Omega Centauri, we make use of a chemical
evolution model that has proven able to reproduce other major observed
properties of the cluster, namely, its stellar metallicity distribution
function, age-metallicity relation and trends of several abundance ratios with
metallicity. In this framework, the key condition to satisfy all the available
observational constraints is that a galactic-scale outflow develops in a much
more massive parent system, as a consequence of multiple supernova explosions
in a shallow potential well. This galactic wind must carry out preferentially
the metals produced by explosive nucleosynthesis in supernovae, whereas
elements restored to the interstellar medium through low-energy stellar winds
by both asymptotic giant branch (AGB) stars and massive stars must be mostly
retained. Assuming that helium is ejected through slow winds by both AGB stars
and fast rotating massive stars (FRMSs), the interstellar medium of Omega
Centauri's parent galaxy gets naturally enriched in helium in the course of its
evolution.
