Constraining the Abundances and Ages of Early-type Galaxies

Abstract

We consider the extent to which broadband mid-UV (2000 - 3000 Angstrom) colors can give superior constraints on the ages and abundances of old stellar populations than can their optical counterparts. The ultraviolet colors directly measure the turnoff component of old populations. They vary much more strongly with t and Z and give much tighter constraints for a given degree of observational precision than do optical-band indices. We present an analysis of the permitted range of (t,Z) arising from observational uncertainties in observations of early-type galaxies.