9542(  1) - 12/06/01 12:47  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9542
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:49:44

1.Proposal Title:
Surface Brightness Profiles for Globular Clusters
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Karl Gebhardt                     University of Texas at Austin
   CoI: Ms. Eva Noyola                    University of Texas at Austin                 N

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5. Abstract

The central surface brightness and luminosity density profiles in any stellar system
are crucial for understanding the governing dynamical processes. Those profiles for
galaxies are well-measured by HST and have been used to make significant scientific
progress. Globular clusters, on the other hand, do not have a well established
dataset for their central surface brightness profiles. Yet, the archive is ripe with
high signal-to-noise data on globular clusters. We will measure the central surface
brightness profiles for about 30 globular clusters. We have searched the archives
for those clusters with adequate signal to provide robust estimates of their central
profile. This data will be combined with our extensive radial velocity dataset in
the central regions to provide a unique opportunity to explore the central dynamics.
The radial velocities show a dramatic increase in the rotational signature at small
radii. Interpretation of this result requires a detailed understanding of the
central surface brightness profiles. Any future endeavor to study globular cluster
dynamics must include the central profiles. We have reached the point where the
kinematics have been analysed to better spatial resolution, and this proposal
addresses the need to place the surface brightness profiles on a more firm level.
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                                                9542(  1) - 12/06/01 12:47  - [  2]

            Summary Form for Proposal  9542

  Item                         Used in this proposal
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  Proposal Category            AR
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