AAS Meeting #193 - Austin, Texas, January 1999
Session 9. Elliptical Galaxies
Display, Wednesday, January 6, 1999, 9:20am-6:30pm, Exhibit Hall 1

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[9.04] Constraints on the Formation History and Mass Distribution of NGC~4472 from Spectroscopy of 150 of its Globular Clusters

S.E. Zepf (Yale U.), M.A. Beasley, R.M. Sharples (Durham U.), T.J. Bridges (IoA, Cambridge), D.A. Hanes (Queens U.), K.M. Ashman (U. of Kansas), D. Giesler (NOAO)

We present the results of an ongoing spectroscopic survey of globular clusters around the giant elliptical galaxy NGC~4472. We have obtained velocities for 144 globulars out to radii of 8' (40 kpc). We discuss dynamical evidence for dark matter in the galaxy from these data. These dynamical constraints are then compared to the mass distribution inferred from X-ray data. We also compare the kinematics of the metal-rich and metal-poor globular cluster populations previously identified through their colors. We find kinematic differences between the populations, confirming the physical distinction between cluster populations of different colors. In particular, the metal-poor cluster population has greater velocity dispersion than the metal-rich population. The metal-rich population also shows no evidence for rotation about any axis. This absence of rotation in the more spatially concentrated and enriched metal-rich population rules out proposed collapse scenarios which lead to the spin-up of this population. However, merger models are consistent with the observations as they provide a known mechanism for angular momentum transport. We also discuss ongoing work that will result in spectra of more clusters and at larger distances from the center of the galaxy.

If you would like more information about this abstract, please follow the link to http://www.astro.yale.edu/zepf/home.html. This link was provided by the author. When you follow it, you will leave the Web site for this meeting; to return, you should use the Back comand on your browser.

The author(s) of this abstract have provided an email address for comments about the abstract: zepf@astro.yale.edu

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