Photometric separation of stellar properties using SDSS filters

Using synthetic photometry of Kurucz model spectra, we explore the colors o f stars as a function of temperature, metallicity, and surface gravity with Sloan Digital Sky Survey (SDSS) filters, u'g'r'i'z'. The synthetic colors show qualitative agreement with the few published observations in these fil ters. We find that the locus of synthetic stars is basically two-dimensiona l for 4500 < T < 8000 K, which precludes simultaneous color separation of t he three basic stellar characteristics we consider. Colors including u' con tain the most information about normal stellar properties; measurements in this filter are also important for selecting white dwarfs. We identify two different subsets of the locus in which the loci separate by either metalli city or surface gravity. For 0.5 < g' - r' < 0.8 (corresponding roughly to G stars), the locus separates by metallicity; for photometric error of a fe w percent, we estimate metallicity to within similar to 0.5 dex in this ran ge. In the range -0.15 < g' - r' < 0.00 (corresponding roughly to A stars), the locus shows separation by surface gravity. In both cases, we show that it is advantageous to use more than two colors when determining stellar pr operties by color. Strategic observations in SDSS filters are required to r esolve the source of a similar to 5% discrepancy between synthetic colors o f Gunn-Stryker stars, Kurucz models, and external. determinations of the me tallicities and surface gravities. The synthetic star colors can be used to investigate the properties of any normal star and to construct analytic ex pressions for the photometric prediction of stellar properties in special c ases.