Classification of galaxies on CCD frames

Abstract

view Abstract Citations (33) References (27) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Classification of Galaxies on CCD Frames van den Bergh, Sidney ; Pierce, Michael J. ; Tully, R. Brent 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 δ(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). Publication: The Astrophysical Journal Pub Date: August 1990 DOI: 10.1086/169027 Bibcode: 1990ApJ...359....4V Keywords: Charge Coupled Devices; Galactic Clusters; Galactic Structure; Interstellar Matter; Corona Borealis Constellation; Planetary Nebulae; Red Shift; Spiral Galaxies; Stellar Luminosity; Virgo Galactic Cluster; Astrophysics; GALAXIES: CLUSTERING; GALAXIES: DISTANCES; GALAXIES: INTERSTELLAR MATTER; GALAXIES: STRUCTURE full text sources ADS | data products NED (231) SIMBAD (227)