9552(  1) - 12/06/01 12:54  - [  1]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      9552
                                                       Version: 1
                                                       Check-in Date: 06-Dec-2001
                                                                      11:51:30

1.Proposal Title:
Using Bars as Signposts of Galaxy Evolution
------------------------------------------------------------------------------------
2. Proposal For  3. Cycle
AR               11
------------------------------------------------------------------------------------
4. Investigators
                                                                                     Contact?
    PI: Kartik Sheth                      California Institute of Technology
   CoI: Dr. Michael Regan                 Space Telescope Science Institute             N

------------------------------------------------------------------------------------
5. Abstract

Recent studies of galaxy morphology with the Hubble Deep Fields have indicated a
dramatic paucity of bars beyond a redshift > 0.5. This result is unexpected because
the classical bar formation mechanism would predict that bars ought to be more
common at higher redshifts because of dynamically colder galaxy disks and increased
interactions. If the scarcity of bars is true, then serious constraints may be
placed on the evolutionary stage of galactic disks. On the other hand, it is
possible that the observations are misleading due to band-shifting and dust
obscuration effects. While these criticisms have been suggested qualitatively, a
quantitative analysis of the evolution of the bar fraction with redshift is missing.
We propose to do such an analysis using the best dataset available for this type of
a study, the NICMOS map of the Hubble Deep Field. For a control sample we will use a
sample of spirals representative of the nearby Universe and simulate their
appearance at different redshifts. From these simulated data, we will measure the
bar fraction for comparison to our analysis of the NICMOS data.
------------------------------------------------------------------------------------
                                                9552(  1) - 12/06/01 12:54  - [  2]

            Summary Form for Proposal  9552

  Item                         Used in this proposal
------------------------------------------------------------------------------------------------------------------------------------
  Proposal Category            AR
------------------------------------------------------------------------------------------------------------------------------------