Session 108 - The Galactic Stellar Disk & Halo.
Display session, Saturday, January 10
Exhibit Hall,

## [108.06] Mass of the Milky Way and Dwarf Spheroidal Stream Membership

G. R. Bell (Harvey Mudd/USNO Flagstaff), S. E. Levine (USNO Flagstaff)

Using radial velocities and the recently determined proper motions for the Magellanic Clouds and the dwarf spheroidal galaxies in Sculptor and Ursa Minor, we have modeled the satellite galaxies' orbits around the Milky Way. Assuming the orbits of the dwarf spheroidals are bound, have apogalacticon less than 300 kpc, and are of low eccentricity, then the minimum mass of our galaxy contained within a radius of 100 kpc is 5.9 \times 10^11M_ødot, and the most likely mass is 7 \times 10^11M_ødot. These mass estimates and the orbit models were used to place limits on the possible maximum tangential velocities and proper motions of the other known dwarf spheroidal galaxies and to assess the likelihood of membership of the dwarf galaxies in various streams.