  Most observations of the projected half-light radii of metal-rich globular
clusters in a variety of galaxies have shown them to be ~20% smaller than those
of their metal-poor counterparts. We show using multi-mass isotropic
Michie-King models that the combined effects of mass segregation and the
dependence of main sequence lifetimes on metallicity can account for this
difference, under the assumption that clusters with similar central potentials
have the same distribution of half mass radii. If confirmed, this would
represent a new constraint on theories of globular cluster formation and
evolution.
