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|Blue compact dwarf galaxies and new velocities in Virgo|
We present new spectral observations of 303 galaxies brighter thanB_J=17.6 in the central 30 deg^2 of the Virgo cluster field. Thegalaxies were selected from two overlapping samples designed for asearch for blue compact dwarf (BCD) galaxies and for a more generalstudy of Virgo dwarf elliptical (dE) galaxies. Many of these galaxieswere designated `background' (i.e., not members of the Virgo cluster) onmorphological grounds by Binggeli, Sandage & Tammann in their VirgoCluster Catalog (VCC). Our principal aim was to measure radialvelocities of these galaxies in order to determine which were members ofthe cluster, looking in particular for any cluster members previouslymisclassified as background galaxies. We measured reliable velocitiesfor 291 galaxies, of which nine were found to be cluster members. Fiveof these were listed in the VCC as `members' and four as `possiblemembers'. We also confirmed that 10 VCC `background' galaxies werecorrectly identified, and determined that an additional three VCC`possible members' were background galaxies. These results show that theVCC membership estimates were generally correct. Our sample of candidateBCD galaxies was defined by objective criteria from digitized platematerial and therefore allows us to place new limits on the dwarf-galaxypopulation. We confirm the drop in the BCD luminosity function at anabsolute magnitude of M_B=-14 reported by Binggeli, Sandage &Tammann (using their Virgo distance modulus). We also show that if BCDsfade 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 limitof B_J=17.6. We use a (U-B_J)(B_J-R_F) colour-colour diagram plottedfrom our photographic data to separate the different dwarf-galaxy typeseffectively and use this colour information to argue that there are noblue star-forming progenitors of dE galaxies in the cluster. Most of thegalaxies of compact appearance we selected were background objects whichwe show to be significantly younger than general field galaxies; thissample also shows considerable clustering in redshift space.
|An image database. II. Catalogue between δ=-30deg and δ=70deg.|
A preliminary list of 68.040 galaxies was built from extraction of35.841 digitized images of the Palomar Sky Survey (Paper I). For eachgalaxy, the basic parameters are obtained: coordinates, diameter, axisratio, total magnitude, position angle. On this preliminary list, weapply severe selection rules to get a catalog of 28.000 galaxies, wellidentified and well documented. For each parameter, a comparison is madewith standard measurements. The accuracy of the raw photometricparameters is quite good despite of the simplicity of the method.Without any local correction, the standard error on the total magnitudeis about 0.5 magnitude up to a total magnitude of B_T_=17. Significantsecondary effects are detected concerning the magnitudes: distance toplate center effect and air-mass effect.
|Optical identifications of the IRAS faint sources in the Virgo cluster area.|
This paper presents a study on the deep optical identifications of 369IRAS faint sources in a 102 square degree area centered on the Virgocluster. We obtained the positions and magnitudes of candidates fromfour UK Schmidt Telescope IIIa-J direct plates. 89 (24%) are identifiedas stars and 276 (75%) as galaxies. There are 4 (1%) empty fields to theplate limit of B=~22. The infrared-optical database for 193 FSC-onlysources is given. Most of the IRAS galaxy sources are spirals. There are83 IRAS galaxy sources being regarded as the cluster members by Binggeliet al. (1985). In our sample, a correlation between the luminosity ratioL_IR_/L_B_ and the infrared flux ratio F(100μm)/F(60μm) isevident. For the member galaxies, a weak correlation between L_IR_/L_B_and L_IR_ is also found.
|HI-observations of galaxies in the Virgo cluster of galaxies. I - The data|
New H I-data for a large number of bright galaxies inside the 10 degradius area of the Virgo cluster of galaxies have been obtained with the100 m radiotelescope at Effelsberg. A total of 234 galaxies was observedfor the first time. Among them, 53 have been detected providing newaccurate radial velocities. Data from the literature have been compiled.Together with the new data, they form a (nearly homogeneous) set of H Iobservations for more than 450 galaxies.
|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.
|On the Largescale Distribution of Faint Blue Galaxies|
|Radial Velocities of Galaxies in the Virgo Cluster|
|Studies of Blue Objects at High Galactic Latitudes. III. Faint Blue Objects in the field of BD + 15° 2469|
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1974A&AS...13..269B&db_key=AST
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