8355(  2) - 12/18/98 16:44  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      8355
                                                       Version: 2
                                                       Check-in Date: 18-Dec-1998
                                                                      16:42:13

1.Proposal Title:
Chemical Abundances and Geometry in QSO Broad Absorption Line Regions
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2. Proposal For  3. Cycle
AR               8
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4. Investigators
                                                                                     Contact?
    PI: Vesa Junkkarinen                  University of California, San Diego
   CoI: Dr. Ross Cohen                    University of California, San Diego           N
   CoI: Dr. Fred Hamann                   University of California, San Diego           N

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5. Abstract

We propose to use archival HST UV spectra to study the chemical abundances in QSO
broad absorption line (BAL) regions while taking into account the geometry of the
emission/absorption regions and, in particular, partial covering of the background
sources by the absorber. Previous studies of BALQSO spectra point to extreme
metallicities, 50 to 100 times solar for some elements (Turnshek et al. 1996) and a
phosphorus to carbon ratio of around 65 times solar (Junkkarinen et al. 1997). Other
studies suggest that the abundances are 1 to 10 times solar (Korista et al. 1996).
The extreme apparent metallicities may result from ignoring, in the analysis,
complex ionization and partial covering effects (Hamann 1998). The combination of
archival HST UV spectra with existing optical spectra (including Keck HIRES spectra)
will provide a better test of both the ionization and partial covering effects. The
UV spectra include many lines and provide constraints on partial covering especially
from saturated lines that are not black. The high resolution Keck spectra of
isolated BALs provide extremely accurate absorption templates and give direct
measurements of partial covering in narrower components in the BAL outflow. An
analysis of BALQSO spectra that includes the background source geometry and partial
covering is now needed before the chemical abundances derived from BALQSOs can be
considered reliable.
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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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                                                8355(  2) - 12/18/98 16:44  - [  2]

            Summary Form for Proposal  8355

  Item                         Used in this proposal
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  Proposal Category            AR
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