8369(  2) - 12/18/98 16:50  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8369
                                                       Version: 2
                                                       Check-in Date: 18-Dec-1998
                                                                      16:48:41

1.Proposal Title:
Evolution of the Symbiotic Nova AG Pegasi
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2. Proposal For  3. Cycle
AR               8
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4. Investigators
                                                                                     Contact?
    PI: Scott J. Kenyon                   Smithsonian Astrophysical Observatory
   CoI: Dr Daniel Proga                   Imperial College of Science, Technology,      N
                                          and Medicine
   CoI: Dr Charles D. (Tony) Keyes        Space Telescope Science Institute             N

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5. Abstract

We propose to study high signal-to-noise FOS and GHRS observations of the symbiotic
nova AG Pegasi. We plan to analyze the ultraviolet spectra together with
contemporaneous low resolution optical spectrophotometry of similarly high quality.
These data will allow us to examine the line and continuum fluxes and radial
velocities at several orbital phases for species with ionization potentials ranging
from ~ 10 eV up to ~ 100 eV. We expect three main results from this program. (i)
Orbital modulation of the emission line fluxes will yield a better understanding of
the geometry of the ionized wind of the red giant primary star. This result will
test our predictions that low ionization lines form near the red giant photosphere
and that higher ionization species lie close to the accreting white dwarf companion.
(ii) Emission line radial velocities will help to constrain the wind geometry and
may place limits on the mass of the white dwarf. (iii) The continuum and emission
line fluxes will test predictions of our non-LTE photoionization code. We have
derived order-of-magnitude estimates for the mass loss rate in the red giant wind
and placed some limits on the velocity law in this wind from archival IUE spectra.
The HST data will yield better constraints on these wind parameters and begin to
test hydrodynamical models for wind accretion in detached binaries.
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  Data Distribution

  Paper Products:  NO
  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
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                                                8369(  2) - 12/18/98 16:50  - [  2]

            Summary Form for Proposal  8369

  Item                         Used in this proposal
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  Proposal Category            AR
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