9535(  1) - 12/06/01 12:44  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9535
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:47:42

1.Proposal Title:
Modeling of HST Observations of O I Emissions of Io in Eclipse
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: David Goldstein                   The University of Texas at Austin
   CoI: Prof. Philip Varghese             The University of Texas at Austin             N
   CoI: Dr. Karl Stapelfeldt              Jet Propulsion Laboratory                     N

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5. Abstract

Observations by Trauger et al with WFPC2 in May 1997 of several bright regions of O
I 630nm emission from Io in eclipse, and lack of ionized S II emission, may be
interpreted to yield information about how Io interacts with the Jovian
magnetosphere. A patchy corona was seen along the limb at high altitude which was
generally brighter on the side of Io facing the plasma stream. It also tended to be
brighter in the plasma wake region near 340^o long., +20^o lat.. Yet these
observations remain to be fully examined in terms of impingement of plasma from the
Jovian torus on volcanic plumes and a sublimation atmosphere. We have recently been
developing the ability to simulate the interaction of plasma particles with Io's
neutral SO_2 atmosphere. We have integrated our Monte Carlo flow field modeling with
a line-by-line radiation code so we can determine radiation and absorption spectra
along any line of sight. We propose to utilize our existing computer code to sum
together separate volcanic and sublimation solutions for the atmosphere at the time
of the 1997 observations. Into such a 3D steady-state instantaneous flow field we
can project a plasma stream bombardment to model the O I and S II emission using the
recently developed ``overlay'' approach to model absolute surface brightness and
spatial distribution from minor species. The proposed work is a collaboration
between one of the original observers and modellers.
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                                                9535(  1) - 12/06/01 12:44  - [  2]

            Summary Form for Proposal  9535

  Item                         Used in this proposal
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  Proposal Category            AR
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