Dynamics of M31 Compact Stellar Systems

Michael Gregg (U. Cal. Davis) & Arna Karick (Liverpool JMU)

Using Keck HIRES and Laser Guide Star Adaptive Optics imaging, we have determined velocity dispersions 
and core sizes of M31 compact stellar systems (globular clusters and ultra-compact galaxies).  This 
enables determination of the masses and mass-to-light ratios of these objects.  In most cases, simple 
stellar population models can account for the internal dynamics and M/L ratios, just as for globular clusters 
in the Milky Way.  We discuss the implications for the nature of ultra-compact dwarfs and other low 
luminosity compact systems.

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Note: This is submitted as a poster because I have submitted another topic as an oral presentation.  We 
may wish to switch the two as our research proceeds, and possibly even switch the order of the authors 
(A. Karick will be a co-author on the oral presentation as well).