10685(  1) - 04/05/05 12:37  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      10685
                                                       Version: 1
                                                       Check-in Date: 05-Apr-2005
                                                                      16:37:19

1.Proposal Title:
The co-evolution of spiral structure and mass distribution in disk galaxies
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2. Proposal For  3. Cycle  4. Parallel Pointing Tolerance
AR               14        <none>
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5. Investigators
                                                                                     Contact?
    PI: Dr. Marc S. Seigar                University of California - Irvine
   CoI: Dr. Aaron J. Barth                University of California - Irvine             N
   CoI: Dr. James Bullock                 University of California - Irvine             N

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6. Abstract

We propose to use a new diagnostic tool to study the mass buildup in disk galaxies
as a function of look-back time out to z~1. The tight correlation between spiral arm
pitch angle and rotation curve shear rate (Seigar et al. 2005) demonstrates that the
tightness of spiral structure in disk galaxies depends on the central mass
concentration (including dark matter), as this determines the shear rate. Galaxies
with high central mass concentration have a higher shear rate and more tightly wound
spiral structure than those with low mass concentration. As a result, the evolution
of spiral structure over time can be used to search for evolution in the mass
distribution in spiral galaxies. The main goal of this project is to determine
evolution in the mass distribution of disk galaxies, using spiral arm pitch angles
as a quanitative indicator. In order to do this we will use nearly face-on disk
galaxies with measurable spiral structure, observed in the GOODS fields.
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                                                10685(  1) - 04/05/05 12:37  - [  2]

            Summary Form for Proposal  10685

  Item                         Used in this proposal
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  Proposal Category            AR
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