7538(  1) - 12/14/96 00:48  - [  0]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7538
                                                       Version: 1
                                                       Check-in Date: 13-Dec-1996
                                                                      18:19:17

1.Proposal Title:
Abundances and Physical Conditions in the Low and Intermediate Velocity Gas Toward
Mu Columbae
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2. Scientific Category   3. Proposal For  4. Cycle
INTERSTELLAR MATTER         AR               7
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5. Investigators
                                                                                     Contact?
    PI: Blair D. Savage                   University of Wisconsin-Madison
   CoI: Christopher Howk                  University of Wisconsin-Madison               N

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6. Abstract

The interstellar path to the O9.5 V star Mu Columbae (l=237degrees, b=-27degrees;
d=1100 pc, z=-485 pc) intercepts several clouds of differing physical conditions.
The lowest velocity clouds sampled are typical of warm diffuse clouds, while the
higher velocity components appear to be examples of shocked-processed clouds, as
evidenced by their enhanced gas phase abundances. Copernicus observations measured
OVI absorption, thus also providing evidence that hot gas exists along this
sightline. During the post-COSTAR orbital verification program, an extremely rich,
high quality data set was obtained for Mu Col with the GHRS echelle gratings. This
extensive data set represents the most complete observations of any interstellar
path, including that towards Zeta Ophiuchi. We will analyze these 3.5 km s^-1
resolution data to derive important information about the patterns of elemental
abundances in the warm neutral medium of the Galaxy, the shock destruction of
interstellar grains in intermediate velocity clouds and the origin of highly ionized
disk gas. The abundances measured for the principal diffuse cloud at V_\mathrm LSR=3
\nolinebreak km s^-1 will provide the fundamental reference data for gas-phase
elemental abundances in the low-density warm interstellar medium of the Galaxy and
will be an important complement to the well studied dense cloud abundances towards
Zeta Oph.
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  Data Distribution

  Media:           ELECTRONIC
  Blocking Factor: 10
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                                                7538(  1) - 12/14/96 00:48  - [  1]

            Summary Form for Proposal  7538

  Item                         Used in this proposal
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  Proposal Category            AR
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  Scientific Category          INTERSTELLAR MATTER
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