ABSTRACT

Omega Centauri is the largest of the Galaxy's globular clusters, and for a long time it was the only one known to contain more than a single, simple population of stars. Over the last few years we have gone from knowing it has some mix of populations to understanding quite a bit more about the various populations: their age, their Helium abundance, and their spatial distributions. I will give a brief summary of what we have learned about this cluster, which many believe to be a transition object between clusters and galaxies. The fact that it has a lot of galaxy-like attributes makes Omega Cen a natural place to look for an intermediate-mass black hole (IMBH). A recent finding by Noyola, Gebhardt,and Bergmann suggests that it may house an even larger IMBH than the M-sigma relation for galaxies would suggest. We use HST to measure proper motions for stars at the center in search for evidence of an intermediate-mass black hole.