Structure and stellar content of dwarf elliptical galaxies.

A small number of low-luminosity elliptical galaxies in the Virgo cluster and around other prominent galaxies have been studied using photoelectric and photographic techniques. The color-magnitude relation for ellipticals now extends from M_v = -23 to -15, and is linear over the range with a slope of 0.10 in U-V per visual magnitude. Galaxies which are known to contain a large number of young stars are from 0.10 to 0.20 mag bluer in U-V than the lower envelope of the dwarf elliptical color-magnitude relation. Surface brightness profiles of the dwarfs have revealed some interesting distinctions between themselves and the brighter E's. Their intensity profiles are shallower than those of the bright E's, meaning they are of lower mean density. These mean densities are also a function of the total luminosity. The flattening distribution of the dwarfs is like that of the bright ellipticals, and is also similar to the flattening distribution of field irregular galaxies.