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[*] An HST study of the central kinematics of M15
Gerssen J., van der Marel R.P., Gebhardt K., Guhathakurta P., Peterson R., Pryor C.
in `New Horizons in Globular Cluster Astronomy', Piotto G., Meylan G., Djorgovski G., Riello M., eds., ASP Conference Series, in press, 2003
© 2003. Astronomical Society of the Pacific. All Rights Reserved.

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 significantly 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 December 8, 2002.
Roeland van der Marel, marel@stsci.edu.
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