Globular Cluster Formation at High Density: A model for Elemental
  Enrichment with Fast Recycling of Massive-Star Debris
  The self-enrichment of massive star clusters by p-processed elements is shown
to increase significantly with increasing gas density as a result of enhanced
star formation rates and stellar scatterings compared to the lifetime of a
massive star. Considering the type of cloud core where a globular cluster might
have formed, we follow the evolution and enrichment of the gas and the time
dependence of stellar mass. A key assumption is that interactions between
massive stars are important at high density, including interactions between
massive stars and massive star binaries that can shred stellar envelopes.
Massive-star interactions should also scatter low-mass stars out of the
cluster. Reasonable agreement with the observations is obtained for a cloud
core mass of ~4x10^6 M_sun and a density of ~2x10^6 cm^{-3}. The results depend
primarily on a few dimensionless parameters, including, most importantly, the
ratio of the gas consumption time to the lifetime of a massive star, which has
to be low, ~10%, and the efficiency of scattering low-mass stars per unit
dynamical time, which has to be relatively large, such as a few percent. Also
for these conditions, the velocity dispersions of embedded globular clusters
should be comparable to the high gas dispersions of galaxies at that time, so
that stellar ejection by multi-star interactions could cause low-mass stars to
leave a dwarf galaxy host altogether. This could solve the problem of missing
first-generation stars in the halos of Fornax and WLM.
