CfA Colloquium Schedule Fall 2005
 29 September 2005

29 September 2005

Speaker: Gary Da Costa (Mt. Stromlo Observatory, The Australian National Observatory)

Title: The Structure of the Sculptor and Fornax Dwarf Spheroidal Galaxies

Abstract: The dwarf Spheroidal (dSph) companion galaxies to the Milky Way are generally accepted as among the 'darkest' galaxies known, with mass-to-light ratios exceeding 100 or more in some cases. The alternative to the high M/L ratios is that the dSphs are not in virial equilibrium, but are instead undergoing tidal disruption by the Milky Way. We have used wide field imaging to investigate the outer structure of two southern dSphs in order to constrain their level of interaction with the Galaxy. For Sculptor, we find little evidence for any such interaction. The outer structure of Fornax, however, is surprisingly complex though we argue that this is not the result of gravitational interaction with the Milky Way.

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