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|Nucleated dwarf elliptical galaxies in the Virgo cluster|
Using images from a charge-coupled device survey with the Wide FieldCamera on the Isaac Newton Telescope, we performed B- and I-bandphotometry on 156 Virgo cluster dwarf elliptical (dE) galaxies, 25candidate new cluster dwarfs, and nine candidate field dwarfs. Galaxieswere modelled with Sérsic profiles, using both 1Dχ2 and 2D cross-correlation methods, with nuclei modelledas point sources. The intensity profiles of 50 galaxies previouslyclassified as dE, dE?, or ? are more accurately fitted if a nucleus isincluded, and this results in the majority of dwarfs now beingclassified as nucleated dwarf ellipticals (dE,N). Some faint galaxieswith B magnitudes of 18-21 have particularly large relative nuclei,while a small number have apparent central dimmings. For cluster dE,Ngalaxies the nucleus magnitude is correlated with the magnitude of thehost galaxy. The profile parameters of dE and dE,N galaxies are notsignificantly different, and there is no evident discontinuity inrelative nucleus size between non-nucleated and nucleated dwarfs,suggesting that they may form a continuum. Nuclei are on average redderthan their underlying galaxies, though a spread of relative colours wasfound, and two-fifths of nuclei are bluer. Formation mechanisms ofnuclei are discussed: at least some appear to have formed in an alreadyexisting non-nucleated galaxy, though others may have formedsimultaneously with their galaxies and subsequently evolved within them.
|The luminosity function of the Virgo Cluster from MB=-22 to -11|
We measure the galaxy luminosity function (LF) for the Virgo Clusterbetween blue magnitudes MB=-22 and -11 from wide-fieldcharge-coupled device (CCD) imaging data. The LF is only graduallyrising for -22
|Studies of the Virgo Cluster. II - A catalog of 2096 galaxies in the Virgo Cluster area.|
The present catalog of 2096 galaxies within an area of about 140 sq degapproximately centered on the Virgo cluster should be an essentiallycomplete listing of all certain and possible cluster members,independent of morphological type. Cluster membership is essentiallydecided by galaxy morphology; for giants and the rare class of highsurface brightness dwarfs, membership rests on velocity data. While 1277of the catalog entries are considered members of the Virgo cluster, 574are possible members and 245 appear to be background Zwicky galaxies.Major-to-minor axis ratios are given for all galaxies brighter than B(T)= 18, as well as for many fainter ones.
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