8358(  2) - 12/18/98 16:46  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8358
                                                       Version: 2
                                                       Check-in Date: 18-Dec-1998
                                                                      16:43:47

1.Proposal Title:
A COMPLETE CENSUS OF HOT STARS IN GLOBULAR CLUSTERS
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2. Proposal For  3. Cycle
AR               8
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4. Investigators
                                                                                     Contact?
    PI: Wayne Landsman                    Raytheon STX
   CoI: Prof. Robert O'Connell            University of Virginia                        N
   CoI: Mr. Theodore Stecher              Goddard Space Flight Center                   N
   CoI: Dr. Marcio Catelan                Goddard Space Flight Center/Hubble Fellow     N
   CoI: Dr. Noella D'Cruz                 University of Washington                      N

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5. Abstract

We propose to assemble a catalog of ultraviolet fluxes and colors for a complete
sample of about 4000 hot stars in twelve globular clusters. For these clusters there
are available both archival WFPC2 images of the cluster cores, and wide- field (40')
images obtained with the Ultraviolet Imaging Telescope (UIT). The UIT data provide a
complete census of the hot stars but lack the color information which can only be
provided in the cluster cores by high resolution WFPC2 photometry. We will use this
catalog of hot stars to explore aspects of their astrophysics that are presently
poorly understood. Specifically, we will (1) test evolutionary tracks of hot
horizontal branch (HB) stars by comparing number counts of different phases (2)
search for radial gradients in the relative populations of extreme HB (EHB) and blue
HB stars, (3) search for statistically significant gaps in the temperature
distribution of hot HB stars (which can provide key clues to physical processes
taking place in red giant branch stars, such as mass loss and deep mixing), and (4)
assemble a complete catalog of ``exotic'' hot stars in the twelve globular clusters.
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  Data Distribution

  Paper Products:  NO
  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
  Email:
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                                                8358(  2) - 12/18/98 16:46  - [  2]

            Summary Form for Proposal  8358

  Item                         Used in this proposal
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  Proposal Category            AR
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