9522(  1) - 12/06/01 12:34  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9522
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:44:21

1.Proposal Title:
Dynamics of Stars and Gas in Double- Barred Galaxies
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2. Proposal For  3. Cycle
AR               11
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4. Investigators
                                                                                     Contact?
    PI: Linda Sparke                      University of Wisconsin-Madison
   CoI: Dr. Witold Maciejewski            Jagiellonian University Observatory,          N
                                          Cracow

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5. Abstract

About half of all spiral and S0 galaxies are barred: recent observations show that
the main bar often harbors one, and sometimes two, smaller `nuclear bars'. The
gravitational potential of these inner bars will strongly influence the flow of gas
in the central regions. Because dynamical times in the central galaxy are short,
small nuclear bars can start growing well before the disk assembly is complete.
Early in a galaxy's history, these central bars may have acted to funnel gas inward
to allow rapid growth of the central black holes that power active nuclei, before
the black hole's strengthening gravity shuts off the inflow, or destroys the bar. A
central bar can also prevent a youthful disk from developing a larger, kiloparsec-
scale bar, until the disk has grown far enough in radius to accomodate an outer bar
that is suitably larger than the inner one. To explore these scenarios, we propose
to use our novel method of emphinvariant loops, to investigate which combinations of
bar mass, size, axis ratio and pattern speed allow `dynamically possible' double-bar
systems. Using hydrodynamic simulations, we will follow the fate of gas in such
systems, and compare the flow patterns to those observed in STIS studies of galaxy
centers. Finally, gravitational \nbody simulations will allow us to build
gravitationally-self-consistent double-bar models, and to predict stellar motions
within them.
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                                                9522(  1) - 12/06/01 12:34  - [  2]

            Summary Form for Proposal  9522

  Item                         Used in this proposal
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  Proposal Category            AR
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