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[*] The Central Mass Concentration in M15
Gerssen J., van der Marel R.P., Gebhardt K., Guhathakurta P., Peterson R.C., Pryor C.
in Carnegie Observatories Astrophysics Series, Vol. 1: Coevolution of Black Holes and Galaxies, ed. L. C. Ho (Pasadena: Carnegie Observatories, http://www.ociw.edu/ociw/symposia/series/symposium1/proceedings.html), in press, 2003

We have obtained stellar absorption line spectra with STIS to measure the radial velocities of individual stars in the crowded center of the globular cluster M15. These data increase the number of stars with known radial velocities within the central arcsec by a factor of about three and signficantly improve the constraints on the mass distribution in M15. The data provide the most detailed look of the central structure of any globular cluster and show that there is a compact dark central mass component. Whether this is due to an intermediate mass black hole or to normal mass segregation cannot yet be uniquely established. However, the former does provide a plausible interpretation of the data. If there is indeed a black hole, its mass is consistent with the relation between velocity dispersion and black hole mass that has been established for galaxies.

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Last modified March 30, 2003.
Roeland van der Marel, marel@stsci.edu.
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