AAS 200th meeting, Albuquerque, NM, June 2002
Session 10. Globular Star Clusters
Display, Monday, June 3, 2002, 9:20am-6:30pm, SW Exhibit Hall

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[10.06] Surface brightness profiles from HST observations of Globular Clusters

E. Noyola, K. Gebhardt (University of Texas at Austin)

We present surface brightness profiles for 27 globular clusters observed with WFPC2 on Hubble Space Telescope. An important tool for studying any dynamical system is using the surface brightness profile to obtain the luminosity density. Traditionally, surface brightness profiles for globular clusters have been described with King models, which have isothermal cores. We try to measure non-zero slope for the luminosity density profiles, since this would have a significant effect on the system structure and evolution. In addition, for core-collapse clusters, the central slopes provide a strong constraint on theoretical models. The profiles are obtained by measuring residual light after substracting bright stars also including that obtained from star counts. The clusters in or sample span a range of surface brightness shapes, from core-collapse to very low concentration clusters. We compare the profile shapes with various fundamental parameters for globular clusters, similar to those correlations seen in the centers of galaxies. Furthermore, we will compare the central stellar density profiles to central kinematics profiles obtained with ground-based data.

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Bulletin of the American Astronomical Society, 34
© 2002. The American Astronomical Soceity.