11245(  1) - 03/30/07 11:04  - [  1]

                  HUBBLE SPACE TELESCOPE OBSERVING PROGRAM 11245

Version: 1    Check-in Time: 30-Mar-2007 15:04:05       STScI Edit Number: 0

Title
Mining the Rich Archive for 47 Tucanae
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Type             Cycle     Parallel Pointing Tolerance
AR               16        <none>
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Investigators
                                                                                     Contact?
    PI: Dr. Peter D. Edmonds              Eureka Scientific Inc.
   CoI: Dr. Ronald L. Gilliland           Space Telescope Science Institute             N
   CoI: Prof. Jonathan E. Grindlay        Harvard University                            N
   CoI: Dr. Maureen van den Berg          Harvard University                            N
   CoI: Dr. Craig Heinke                  Northwestern University                       N
   CoI: Dr. Vinay Kashyap                 Smithsonian Institution Astrophysical         N
                                          Observatory

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Abstract

We propose to capitalise on the extensive set of scientific and calibration
observations of the remarkable globular cluster 47 Tuc. The chief goals are: (1) to
address key questions about the binaries found in this massive cluster, including
studies of cataclysmic variables (CVs), low-mass X-ray binaries (LMXBs), millisecond
pulsars (MSPs) and chromospherically active binaries, and (2) to study a dynamically
important but thus far neglected class of binaries, containing subgiant and giant
stars. We plan to make the most extensive analysis to date of long-term variability
in globular cluster binaries, including searches for dwarf nova outbursts, high and
low states and periodic variations for CVs; study accretion rate changes for LMXBs;
study active binaries that appear to undergo coronal mass ejections; identify the
nature of two binaries that experience incredibly bright X-ray flares; confirm new
candidates of rare MSPs with main sequence companions; search for optical IDs of
unidentified Chandra sources. This is the richest population of binaries known in
any globular cluster and the complete archival dataset is unlikely to be rivaled for
many years. These studies will add to our understanding of this important crash-test
laboratory and have broader implications for stellar dynamics, stellar and binary
evolution and globular cluster evolution.
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