AAS 205th Meeting, 9-13 January 2005
Session 142 Galactic Structure, Halo and High Velocity
Poster, Thursday, January 13, 2005, 9:20am-4:00pm, Exhibit Hall

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[142.02] Observing Dynamical Friction using the Sagittarius Dwarf Galaxy's Tidal Streams

C. B. Hummels, K. V. Johnston (Wesleyan University), S. R. Majewski (University of Virginia), D. R. Law (Caltech)

Our close neighboring galaxy at only 16 kpc from the Galactic center, Sagittarius (Sgr) exhibits the most dramatic gravitational stripping of any local galaxies with stellar tidal streams observed extending entirely around the Milky Way. Recent observations in dynamically older sections of the tidal tails demonstrate that extant numerical models of Sgr's orbit are inadequate to fit all available stream data. One interpretation of this data suggests that Sgr's orbit was more distant in the past and is spiraling in toward the Galactic center. This effect can be explained by dynamical friction, the drag force acting on a body as it travels through a field of point masses, a reasonable approximation of the Milky Way halo. Using numerical simulations which take into account dynamical friction, we seek to reproduce the full phase-space distribution of stars in Sgr's streams. This investigation could yield the first direct observation of dynamical friction in action.

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