Project summary

In this project we show that H burning in main-sequence stars of ~10,000 solar masses could explain all the proton-capture element abundance anomalies observed in Glactic globular clusters.

We propose that the abundance anomalies of proton-capture elements in globular clusters, such as the C-N, Na-O, Mg-Al and Na-F anti-correlations, were produced by super-massive stars with M~10,000 solar masses. Such stars could form in the runaway collisions of massive stars that sank to the cluster centre as a result of dynamical friction, or via the direct monolithic collapse of the low-metallicity gas cloud from which the cluster formed. To explain the observed abundance anomalies, we assume that the super-massive stars had lost significant parts of their initial masses when only a small mass fraction of hydrogen, ΔX~0.15, was transformed into helium. We speculate that the required mass-loss might be caused by the super-Eddington radiation continuum-driven stellar wind or by the diffusive mode of the Jeans instability.