1998/12/01 by Taft E. Armandroff, Gary S. Da Costa
Physics and Astronomy · #astro-ph
published as in "The Stellar Content of Local Group Galaxies", IAU Symposium 192, ed. P. Whitelock & R. Cannon, page 203 (1999) · To be published in "The Stellar Content of Local Group Galaxies", Proceedings of IAU Symposium 192, edited by P. Whitelock and R. Cannon; 1 embedded PostScript figure, 1 JPEG figure
arxiv created 1998/12/01 · arxiv updated 2009/12/01
Our current knowledge of M31's dwarf spheroidal companions is reviewed. Two topics of recent interest constitute the bulk of this review. First, color-magnitude diagrams reaching below the horizontal branch have been constructed for two M31 dwarf spheroidals based on images from HST/WFPC2. The horizontal branches are predominantly red in both galaxies, redder than expected for their metallicity based on Galactic globular clusters. Thus, the second parameter effect is seen in the M31 halo. Second, recent surveys have revealed three new dwarf spheroidal companions to M31. Thus, dwarf spheroidal galaxies are not as rare around M31 as previously thought and as a result, some properties of the M31 companion system have changed.