THE ASTRONOMICAL JOURNAL    VOLUME 110, NUMBER 5, PAGE 1959       NOVEMBER 1995

   A 20cm VLA SURVEY OF ABELL CLUSTERS OF GALAXIES. V. OPTICAL OBSERVATIONS
                            AND SURFACE PHOTOMETRY

                               MICHAEL J. LEDLOW

             New Mexico State University, Department of Astronomy,
                         Las Cruces, New Mexico 88003
                       Electronic mail: mledlow@nmsu.edu

                                FRAZER N. OWEN

        National Radio Astronomy Observatory, Socorro, New Mexico 87801
                      Electronic mail: fowen@aoc.nrao.edu


                                   ABSTRACT

    We present results from a program of optical imaging of 265 radio
    galaxies in rich clusters.  Using isophotal surface photometry, we
    investigate the optical properties such as the morphology, surface-
    brightness profiles, surface-brightness/size relationships,
    ellipticities, and the frequency of nonelliptical isophotes.  The
    results are compared to a "normal" nonradio-selected sample of
    elliptical galaxies from the same clusters.  The goal is to determine
    if the parent population of FR I radio galaxies can be distinguished
    optically from radio-quiet galaxies.  The results of the analysis are
    that cluster ellipticals are a very homogeneous class of objects.  The
    optical properties are consistent with a one-parameter family, where
    the optical luminosity is the fundamental parameter.  In all tests
    considered, radio-loud FR I galaxies cannot be distinguished optically
    from radio-quiet galaxies selected from the same environment.  The
    local density of nearby companions (<20 kpc) and the frequency of
    morphological peculiarities or tidal interactions are not statistically
    different between the radio-loud and quiet samples.  There is some
    suggestion from comparison to published samples of non-cluster radio
    galaxies, that the cluster environment is not condusive to long-lived
    tidal interactions, and that such events may be more important to
    galaxy evolution in poor groups and lower density environments.  Such
    events appear to have little influence on the formation of FR I radio
    galaxies in rich clusters.  The results are consistent with the idea
    that all elliptical galaxies may at some time (or many times) contain
    powerful (FR I) radio sources.