Population Gradients in Local Group Dwarf Spheroidal Galaxies

Abstract

We present a systematic and homogeneous analysis of population gradients for\nthe Local Group dwarf spheroidals (dSphs) Carina, Sculptor, Sextans, Tucana,\nAndromeda I-III, V, and VI. For all of the Milky Way companions studied here we\nfind significant population gradients. The same is true for the remote dSph\nTucana located at the outskirts of the LG. Among the M 31 dSph companions only\nAndromeda I and VI show obvious gradients. In all cases where a HB morphology\ngradient is visible, the red HB stars are more centrally concentrated. The\noccurence of a HB morphological gradient shows a correlation with a morphology\ngradient in the red giant branch. It seems likely that metallicity is the\ndriver of the gradients in Sextans, Sculptor, Tucana, and Andromeda VI, while\nage is an important factor in Carina. We find no evidence that the vicinity of\na nearby massive spiral galaxy influences the formation of the population\ngradients.\n