Globular Cluster Mass Loss in the Context of Multiple Populations
  Many scenarios for the origin of the chemical anomalies observed in globular
clusters (GCs; i.e., multiple populations) require that GCs were much more
massive at birth, up to $10-100\times$, than they are presently. This is
invoked in order to have enough material processed through first generation
stars in order to form the observed numbers of enriched stars (inferred to be
second generation stars in these models). If such mass loss was due to tidal
stripping, gas expulsion, or tidal interaction with the birth environment,
there should be clear correlations between the fraction of enriched stars and
other cluster properties, whereas the observations show a remarkably uniform
enriched fraction of $0.68\pm0.07$ (from 33 observed GCs). If interpreted in
the heavy mass loss paradigm, this means that all GCs lost the same fraction of
their initial mass (between $95-98$\%), regardless of their mass, metallicity,
location at birth or subsequent migration, or epoch of formation. This is
incompatible with predictions, hence we suggest that GCs were not significantly
more massive at birth, and that the fraction of enriched to primordial stars
observed in clusters today likely reflects their initial value. If true, this
would rule out self-enrichment through nucleosynthesis as a viable solution to
the multiple population phenomenon.
