Infrared photometry and optical spectroscopy of dwarf galaxies in theVirgo cluster.

A small number of dwarf elliptical galaxies in the Virgo Cluster have been observed in the infrared using the MMT infrared photometer. In addition, spectroscopy of one of the more nucleated dwarfs in the sample has been performed. These data can be combined with the optical photometry of Caldwell (1983) in order to derive B - H colors. The limited data set reveals that the B - H colors of Virgo dwarfs are systematically bluer, by 0.5-1 mag, than more luminous elliptical galaxies. This straightforwardly suggests that the light from these dwarfs is dominated by giants with metallicities substantially less than those which populate giant ellipticals. Alternatively, their bulk age may be considerably less than the ages of giant ellipticals.