We discuss the application of the internal color dispersion to high-redshift galaxies in deep Hubble Space Telescope images. Elliptical, lenticular, and early-type spiral galaxies generally have low or negligible internal color dispersion, which indicates that the stars contributing to the ultraviolet-optical emission have a very homogeneous distribution. This implies that young stars generally dominate the ultraviolet-optical galaxy colors, modulo variations in the dust, gas, and stellar distributions. Irregular and late-type spiral galaxies show moderate internal color dispersion, although with lower values relative to the mid-type spirals.
Mid-type spiral galaxies exhibit the highest dispersion in their ultraviolet-optical internal colors, which stems from differences in the stellar content that constitute the bulge, disk, and spiral-arm components. In general, the dispersion in the internal galaxy colors correlates with transformations in the galaxy morphology as a function of wavelength i.e., our internal color dispersion statistic quantifies the morphological K-correction. We apply this statistic to a sample of local galaxies with archival images at 15 Å from the Ultraviolet Imaging Telescope and ground-based B-band observations in order to investigate how the internal dispersion between these colors relates to global galaxy properties (e.g., luminosity, color, and morphological type). We present a quantitative measure of the internal color dispersion within galaxies, which quantifies differences in galaxy morphology as a function of observed wavelength.
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