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For refcode 1996MNRAS.279..595D:
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Copyright by Royal Astronomical Society. 1996MNRAS.279..595D Blue compact dwarf galaxies and new velocities in Virgo M. J. Drinkwater, M. J. Currie, C. K. Young, E. Hardy and J. M. Yearsley Anglo-Australian Observatory, Coonabarabran, New South Wales 2357, Australia Ruthefford Appleton Laboratory, Chilton, Didcot, Oxfordshire OX11 0QX Department of Physics, University of Oxford, Nuclear and Astrophysics Laboratory, Keble Road Oxford OX1 3RH Departement de Physique, Observatoire du Mont Megantic, Universite Laval, Quebec, Quebec GIK 7P4, Canada Observatorio Astronomico Nacional, Universidad de Chile, Casilla 3~D, Santiago, Chile School of Mathematics and Physical Sciences, University of Sussex Brighton BN1 9QH Accepted 1995 October 17. Received 1995 August 1; in original form 1994 October 24 ABSTRACT We present new spectral observations of 303 galaxies brighter than B_J_ = 17.6 in the central 30 deg^2^ of the Virgo cluster field. The galaxies were selected from two overlapping samples designed for a search for blue compact dwarf (BCD) galaxies and for a more general study of Virgo dwarf elliptical (dE) galaxies. Many of these galaxies were designated `background' (i.e., not members of the Virgo cluster) on morphological grounds by Binggeli, Sandage & Tammann in their Virgo Cluster Catalog (VCC). Our principal aim was to measure radial velocities of these galaxies in order to determine which were members of the cluster, looking in particular for any cluster members previously misclassified as background galaxies. We measured reliable velocities for 291 galaxies, of which nine were found to be cluster members. Five of these were listed in the VCC as `members' and four as `possible members'. We also confirmed that 10 VCC `background' galaxies were correctly identified, and determined that an additional three VCC `possible members' were background galaxies. These results show that the VCC membership estimates were generally correct. Our sample of candidate BCD galaxies was defined by objective criteria from digitized plate material and therefore allows us to place new limits on the dwarf-galaxy population. We confirm the drop in the BCD luminosity function at an absolute magnitude of M_B_ = - 14 reported by Binggeli, Sandage & Tammann (using their Virgo distance modulus). We also show that if BCDs fade at the end of the current burst of star formation, such `dead' BCDs, if they exist, would all have to be fainter than our sample limit of B_J_ = 17.6. We use a (U - B_J_) (B_J_ - R_F_) colour-colour diagram plotted from our photographic data to separate the different dwarf-galaxy types effectively and use this colour information to argue that there are no blue starforming progenitors of dE galaxies in the cluster. Most of the galaxies of compact appearance we selected were background objects which we show to be significantly younger than general field galaxies; this sample also shows considerable clustering in redshift space. Key words: galaxies: clusters: general - galaxies: clusters: individual: Virgo - galaxies: compact - galaxies: distances and redshifts - galaxies: formation.
Retrieve 377 NED objects in this reference.
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