9546(  1) - 12/06/01 12:49  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9546
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:50:44

1.Proposal Title:
Observational Signatures of Nested Bars in Disk Galaxies
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Isaac Shlosman                    University of Kentucky
   CoI: Dr. Clayton Heller                Georgia Southern University                   N

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5. Abstract

vspace*-.4cm We propose to advance the spectroscopic method of detection of nuclear
bars in nested bar systems. Stellar and gaseous bars on all scales dramatically
change and speed up dynamical and secular evolution of disk galaxies. Due to the
lack of a clear theoretical analysis of kinematic signatures of nuclear bars and of
nested bar dynamics, only photometry is currently used to search for these strongest
of departures from axial symmetry in disk galaxies. This leads to an underestimate
of bar fractions and seriously undermines our understanding of stability and
evolution of these systems, especially on sub-kpc scales. Complete reliance on
photometric studies of nuclear bars, along with theoretical `vacuum,' has also led
to some erroneous results. By means of numerical study of gas and stellar dynamics
in nested bar galaxies, we shall determine observational signatures of nuclear bars
and will utilize available and future HST photometric and spectroscopic data, in
conjunction with ground based observations. Specifically, we shall analyze and make
testable predictions regarding the sense of rotation of nuclear bars, their extent
with respect to the corotation radius, observed stellar velocity reversals, gas
influx across the bar-bar interface, settling of the gas in the nuclear bars and
distribution of shocked gas in nested bars. Nested bars can form a dynamic link
between the nuclear regions and the galaxy at large. Understanding the nested bar
dynamics, and gas and stellar contents, will expose their role in galactic
evolution.
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                                                9546(  1) - 12/06/01 12:49  - [  2]

            Summary Form for Proposal  9546

  Item                         Used in this proposal
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  Proposal Category            AR
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