The hub of the wheel - the nuclear star cluster of the Milky Way

Nuclear star clusters (NSCs) are present at the photometric and dynamical centers of the vast majority of galaxies. They are the densest known clusters in the Universe. Unfortunately, extragalactic NSCs can be barely resolved, even by the HST or ground based adaptive optics observations. This makes the NSC at the center of the Milky Way is a unique target because it can be resolved into tens of thousands of individual stars using current technology. This allows us to study in detail its spatial and velocity structure as well as the different stellar populations that make up the cluster. Moreover, the Milky Way is one of the very few cases where we have firm evidence for the co-existence of a nuclear star cluster with a central supermassive black hole, Sagittarius A*. We present star counts and proper motions for more than 6000 stars within 1 pc in projection from the central black hole. The cluster appears isotropic at pro jected distances >0.5 pc from Sagittarius A*. A robust result of our Jeans modeling of the data is the required presence of 0.5 - 2.0 10^6 M_sol of extended (stellar) mass in the central parsec of the Galaxy.

 

Date: 
16/10/2008 - 14:00
Speaker: 
Rainer Schödel
Filiation: 
Instituto de Astrofísica de Andalucía - CSIC


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