SIMBAD references

We combine spectroscopic metallicity values with integrated narrowband continuum colors to explore the internal metallicity distribution in early-type galaxies. The different techniques for determining metallicity (indices versus colors) allow for an estimate of the contribution from metal-poor stars in a predominantly metal-rich population, which, in turn, places constraints on the shape and width of a galaxy's metallicity distribution function. The color-spectroscopic data are compared with the closed box, infall, and inhomogeneous chemical evolution models. The G-dwarf problem, a deficiency in metal-poor stars as compared with closed-box models, is evident in the data set and indicates that this deficiency is common to all early-type galaxies. However, even simple infall models predict galaxy colors that are too blue compared with the observations. A simple analytical model is proposed that matches the elliptical data and recent Hubble Space Telescope observations of M31 and NGC 5128 by reducing the number of metal-poor stars in a systematic fashion. Without physical justification, the shape of these models is similar to predictions of inhomogeneous enrichment scenarios.