7519(  1) - 12/14/96 00:16  - [  0]

    PROPOSAL FOR HUBBLE SPACE TELESCOPE OBSERVATIONS   ST ScI Use Only
                                                       ID:      7519
                                                       Version: 1
                                                       Check-in Date: 13-Dec-1996
                                                                      18:13:20

1.Proposal Title:
The Rise of Blue Nucleated Galaxies: Evidence for Merger-Induced Evolution?
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2. Scientific Category   3. Proposal For  4. Cycle
GALAXIES                    AR               7
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5. Investigators
                                                                                     Contact?
    PI: Matthew Bershady                  Penn State University
   CoI: Anna Jangren                      Penn State University                         N

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6. Abstract

We propose a detailed study of fundamental photometric properties - surface
brightness, color, and image concentration - of the blue nucleated galaxies (BNGs).
This class of objects was discovered from HST images to be common at intermediate
redshifts, and is characterized by very blue U -V colors and high bulge-to-total
ratios. BNGs are claimed to make up a large fraction of the excess optical counts at
faint magnitudes; their image structure and spectra indicate that their extreme
properties may be caused by merger-induced bursts of star formation. By using multi-
aperture photometry to analyze samples of faint field galaxies at known redshifts,
we plan to refine the selection criteria and to accumulate a set of BNGs which spans
a large range in redshift. This data set will be used to map out the evolution in
number of these peculiar objects, as well as the correlations between their image
structure, color and surface brightness, and how the correlations change with look-
back time. Different scenarios for the origin of the faint blue galaxies will
produce recognizable ``signatures'' in the photometric characteristics, and allow us
to determine if the BNGs are indeed the result of frequent merging of galaxies at
moderate redshifts.
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  Data Distribution

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  Blocking Factor: 10
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                                                7519(  1) - 12/14/96 00:16  - [  1]

            Summary Form for Proposal  7519

  Item                         Used in this proposal
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  Proposal Category            AR
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  Scientific Category          GALAXIES
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