1999/06/24 by S. C. Trager, Trager, S. C.
Physics and Astronomy · #Astrophysics (astro-ph) #FOS: Physical sciences #astro-ph
paper · pdf · doi:10.48550/arxiv.astro-ph/9906396
6 pages, 6 eps figures; to appear in "Photometric Redshifts and High Redshift Galaxies", eds. R. Weymann, L. Storrie-Lombardi, M. Sawicki & R. Brunner. Figure 4 caption revised
arxiv created 1999/06/25 · arxiv updated 2009/12/01
Early-type galaxies are not the simple Population II systems they have long been assumed to be. While upwards of 80% of the stellar mass of early-type galaxies likely formed at high redshift, small frostings of intermediate-age stellar populations (a few to 20% percent by mass of 1-2 Gyr old stars) are present in nearly every field and group early-type galaxy and in at least some cluster early-types. These frostings of young stars have little effect on the determination of photometric redshifts, thanks to the age-metallicity degeneracy of broad-band colors, but even mild bursts of star formation at modest redshifts (a few tenths) may make identification of the progenitors of today's early-type galaxies difficult at cosmological distances.