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For refcode 1990ApJ...359....4v:
Retrieve 231 NED objects in this reference.
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Copyright by American Astronomical Society. Reproduced by permission
1990ApJ...359....4v CLASSIFICATION OF GALAXIES ON CCD FRAMES SIDNEY VAN DEN BERGH AND MICHAEL J. PIERCE Dominion Astrophysical Observatory, National Research Council of Canada AND R. BRENT TULLY Institute for Astronomy, University of Hawaii Received 1989 November 14; accepted 1990 February 9 ABSTRACT New morphological classifications are given for 231 galaxies in or near the Virgo and Ursa Major clusters. It is found that classification of galaxies on CCD frames is more accurate than are classifications based on inspection of photographic plates. Our classifications show that the Virgo Cluster contains a class of spiral galaxies with large central "bulges," that exhibit strong or moderately strong star formation near their centers. The outer regions of these objects frequently exhibit a smooth "anemic" appearance. Very few galaxies of this type were found in the Ursa Major Cluster. It is tentatively suggested that the early-type spiral galaxies with active star formation in their central regions, which are observed in the Virgo Cluster, might represent a mild form of the Butcher-Oemler effect that still survives at zero redshift. For 29 Virgo galaxies with Tully-Fisher distances D < 20 Mpc the mean distance modulus, as derived from luminosity classifications, is (m-M) = 30.93 +/- 0.13 (15.3 Mpc). This may be compared with (m-M) = 31.57 +/- 0.17 (20.8 Mpc) from luminosity classifications of eight galaxies which have Tully-Fisher (TF) distances D > 20 Mpc. The difference between the distance moduli of TF background and cluster members is {delta}(m-M) = 0.66 +/- 0.21. This result strongly supports the conclusion that the large dispersion in the TF relation for galaxies in the Virgo direction is largely due to contamination of the cluster core sample by background galaxies. Adding the 0.31 mag systematic uncertainty in the luminosity of the calibrating galaxies in quadrature yields a distance modulus (m-M) = 30.93 +/- 0.34 (15.3^=2.6^_2.2_ Mpc) for the core of the Virgo Cluster. This value is, within the quoted errors, consistent with recent distance determinations based on planetary nebulae and the Tully-Fisher technique. The dustiness of Virgo and Ursa Major cluster galaxies is found to drop dramatically below B_T_ ~ 13 (M_B_~ -18). Subject headings: galaxies: clustering - galaxies: distances - galaxies: interstellar matter - galaxies: structure
Retrieve 231 NED objects in this reference.
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