8376(  2) - 12/18/98 16:52  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8376
                                                       Version: 2
                                                       Check-in Date: 18-Dec-1998
                                                                      16:51:12

1.Proposal Title:
A Semi-Empirical Model of the Structured Wind of 32 Cygni
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2. Proposal For  3. Cycle
AR               8
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4. Investigators
                                                                                     Contact?
    PI: Philip Bennett                    University of Colorado

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5. Abstract

I propose to construct a semi-empirical wind model of the supergiant primary of the
eclipsing binary 32 Cygni (K5 Iab + B6 V), using archival HST/GHRS observations
obtained at 6 epochs around the December 1996 eclipse. From these observations, I
will empirically determine the hydrogen column density structure along each line of
sight to the early-type secondary star using the Tau--v method. I will use codes
developed for the analysis of HST/GHRS observations of the similar binary Zeta Aur.
Successful Tau--v inversion of the UV absorption line profiles requires high
spectral resolution and high S/N, limiting the useful data to those from HST/GHRS.
Recent HST/GHRS observations of Zeta Aur in Cycles 2 & 5, and of 32 Cyg in Cycle 6,
have shown the primary's wind has discrete structure along some lines of sight.
However, global flux diagnostics such as UV emission line profiles and radio
continuum fluxes, show that the globally-averaged wind is only slightly variable in
time, implying most of the observed variability in the absorption lines is on small
scales. Semi- empirical mean models of these winds are useful. Therefore, I will
construct a semi-empirical model of the mean density, temperature, and velocity
structure of the wind of 32 Cygni. I will also do a radial velocity analysis of the
GHRS spectra of 32 Cyg, in conjunction with eclipse and flux constraints, to obtain
accurate masses and radii of the 32 Cyg stars.
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  Data Distribution

  Paper Products:  NO
  Media:           ELECTRONIC
  Blocking Factor: 10
  Ship To:         PI_Address
  Ship Via:
  Email:
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                                                8376(  2) - 12/18/98 16:52  - [  2]

            Summary Form for Proposal  8376

  Item                         Used in this proposal
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  Proposal Category            AR
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