8052(  1) - 04/30/98 15:14  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8052
                                                       Version: 1
                                                       Check-in Date: 30-Apr-1998
                                                                      15:13:44

1.Proposal Title:
A HST Archival Study of Cataclysmic Variable White Dwarfs
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2. Proposal For  3. Cycle
AR               7
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4. Investigators
                                                                                     Contact?
    PI: Dr. Edward Sion                   Villanova University
   CoI: Dr. Fuhua Cheng                   Villanova University                          N
   CoI: Dr. Paula Szkody                  University of Washington at Seattle           N
   CoI: Dr. S. Starrfield                 Arizona State University                      N
   CoI: Dr. W. Sparks                     LANL                                          N
   CoI: Dr. P. Hauschildt                 University of Georgia                         N
   CoI: Dr. Ivan Hubeny                   NASA/GSFC                                     N

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5. Abstract

HST spectroscopy of faint exposed white dwarfs (WDs) in cataclysmic variables (CVs)
has yielded the first CV white dwarf rotation rates, T_eff, log g, first chemical
abundances of their accreted atmospheres, cooling response to heating of the white
dwarf by accretion (boundary layer irradiation, compression and shear mixing) in
consequence of dwarf nova outburst events, the first HST- determined WD masses
independent of disk emission line velocities, and resulted in the first detection of
an accretion belt. However detailed information is available for ONLY a handful of
systems, and they are dwarf novae with extremely different characteristics. The
white dwarf properties in other CV subgroups have not yet been characterized.
Therefore, the properties of the white dwarfs derived so far in just three dwarf
novae are only individual analyses. In order to progress toward a deeper, broader
(i.e. more global) understanding of both disk and magnetic accretion, it is vital to
enhance our knowledge about the properties of the compact star/boundary layer. This
can ONLY be accomplished by an increased sample size. The HST archival spectra of 14
non-magnetic and magnetic CVs contains untapped new information on the underlying
accreting WDs in AM Her/DQ Her systems and in several other kinds of dwarf novae.
None of these have been analyzed with multi-component (disk, white dwarf, absorbing
curtain, accretion belt) LTE/NLTE synthetic spectral fitting. We propose to carry
out these first detailed studies of the underlying WDs in these systems and thereby
shed further light on the effects of accretion.
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  Blocking Factor: 10
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                                                8052(  1) - 04/30/98 15:14  - [  2]

            Summary Form for Proposal  8052

  Item                         Used in this proposal
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  Proposal Category            AR
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