7540(  1) - 12/14/96 00:51  - [  0]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7540
                                                       Version: 1
                                                       Check-in Date: 13-Dec-1996
                                                                      18:19:54

1.Proposal Title:
An Archival Search for Erupting Dwarf Novae in Globular Clusters
------------------------------------------------------------------------------------
2. Scientific Category   3. Proposal For  4. Cycle
BINARY STARS                AR               7
------------------------------------------------------------------------------------
5. Investigators
                                                                                     Contact?
    PI: Michael Shara                     Space Telescope Science Institute
   CoI: David Zurek                       Space Telescope Science Institute             N

------------------------------------------------------------------------------------
6. Abstract

The archived WFPC2 images of Galactic and Magellanic globular clusters provide us
with a unique opportunity to detect erupting cataclysmic variables (CVs), known as
dwarf novae (DN), in cluster cores where they should be relatively common. Two-body
tidal capture theory predicts that close binary systems should be relatively common
in globular clusters, up to several orders of magnitude greater in relative number
than in the Galactic field. However, only a few confirmed CVs have been discovered
in globular clusters (examined with HST) to date. This paucity of CVs brings into
question dynamical theories which predict great numbers of CVs. We propose to use
the WFPC2 images with multiple epochs in the same (or nearly the same) filter of the
cores of globular clusters to detect outbursting DN. There are 32 clusters which
will have two or more epochs of WFPC2 imaging data after cycle 6. At any given time
~15\ find ~30\ have two epochs. In clusters for which we have three or more epochs
we should find >~50\ demonstrated that this technique works by finding a new
erupting DN in NGC 6624 in archival WFPC2 images. The determination of how many DN
exist in the cores of globular clusters will either support present dynamical
theories or help force the development of alternate theories that can adequately
explain these results.
------------------------------------------------------------------------------------
  Data Distribution

  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
  Email:                                                              ,
------------------------------------------------------------------------------------

                                                7540(  1) - 12/14/96 00:51  - [  1]

            Summary Form for Proposal  7540

  Item                         Used in this proposal
------------------------------------------------------------------------------------------------------------------------------------
  Proposal Category            AR
------------------------------------------------------------------------------------------------------------------------------------
  Scientific Category          BINARY STARS
------------------------------------------------------------------------------------------------------------------------------------