The dwarf spheroidal galaxy Andromeda I

Abstract

Images of Andromeda I in the visual and near-infrared show a giant branch characteristic of Galactic globular clusters of intermediate metallicity. The distance of the galaxy is estimated from the tip of the giant branch to be 790 ± 60 kpc. The physical dimensions and luminosity are similar to those of the dwarf spheroidal in Sculptor. There is no evidence for an intermediate age population in Andromeda I, and appropriate upper limits are specified. There is marginal evidence for a color gradient in the galaxy, a phenomenon not previously noted in a dwarf spheroidal.