9199(  1) - 12/20/00 23:39  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9199
                                                       Version: 1
                                                       Check-in Date: 20-Dec-2000
                                                                      23:32:19

1.Proposal Title:
A Complete Study of Binaries and X-ray Sources in the Globular Cluster 47 Tucanae
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2. Proposal For  3. Cycle
AR               10
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4. Investigators
                                                                                     Contact?
    PI: Jonathan Grindlay                 Harvard-Center for Astrophysics
   CoI: Dr. Peter Edmonds                 Harvard College Observatory                   N
   CoI: Mr. Craig Heinke                  Department of Astronomy, Harvard              N

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5. Abstract

As one of the closest and most massive Galactic globular clusters, and with a
concentrated core, 47 Tuc has a diverse array of binary species including 20
millisecond pulsars, 9 X- ray sources, dozens of blue stragglers and 9 eclipsing
binaries. Our already obtained data includes sensitive V/I time series and easily
the deepest X-ray (Chandra) data ever obtained for 47 Tuc, but precise absolute
photometry from HST is desired to extend and complete our binary studies. By
analyzing two WFPC2 observations in the HST archive we plan to: (1) make the first
photometric determination of the main sequence binary population in this cluster
(this is a fundamental quantity, since MS binaries are the basic fuel for all of the
accreting and compact binaries listed above), (2) confirm and extend our recent
discovery of a new form of binary in this cluster, main sequence/giant star
binaries, and (3) complement our Chandra and HST time series observations of this
superb GC by identifying counterparts to X-ray sources (on the basis of color and
variability), and searching for and studying He WDs and MSP counterparts in this
cluster. Here, we have already made startling progress with the recent exciting
discovery of a counterpart for the second brightest X-ray source in 47 Tuc, X5, a
possible qLMXB, and the possible detection of He WDs. The results of these studies
should have powerful ramifications for the evolution and dynamics of GCs.
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                                                9199(  1) - 12/20/00 23:39  - [  2]

            Summary Form for Proposal  9199

  Item                         Used in this proposal
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  Proposal Category            AR
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