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Completing H I observations of galaxies in the Virgo cluster
High sensitivity (rms noise 0.5 mJy) 21-cm H I line observationswere made of 33 galaxies in the Virgo cluster, using the refurbishedArecibo telescope, which resulted in the detection of 12 objects. Thesedata, combined with the measurements available from the literature,provide the first set of H I data that is complete for all 355 late-type(Sa-Im-BCD) galaxies in the Virgo cluster with mp ≤ 18.0mag. The Virgo cluster H I mass function (HIMF) that was derived forthis optically selected galaxy sample is in agreement with the HIMFderived for the Virgo cluster from the blind HIJASS H I survey and isinconsistent with the Field HIMF. This indicates that both in this richcluster and in the general field, neutral hydrogen is primarilyassociated with late-type galaxies, with marginal contributions fromearly-type galaxies and isolated H I clouds. The inconsistency betweenthe cluster and the field HIMF derives primarily from the difference inthe optical luminosity function of late-type galaxies in the twoenvironments, combined with the HI deficiency that is known to occur ingalaxies in rich clusters.Tables \ref{t1, \ref{sample_dat} and Appendix A are only available inelectronic form at http://www.edpsciences.org
| Broad-band colours of Virgo cluster low surface brightness dwarf irregular galaxies
We present UBVRI images and surface photometry of a complete sample of29 low-luminosity dwarf irregular galaxies in the Virgo cluster, forwhich we derive central surface brightnesses, scalelengths, integratedmagnitudes and median colours. The colour distributions are discussed interms of radial surface brightness profiles, and colour gradients areinterpreted and compared with corresponding ones for lowsurface-brightness (LSB) spiral galaxies. By combining broad-band andnarrow-band filter observations, the past and current influences of thecluster environment on the evolution of LSB dwarf irregular galaxies isevaluated.
| HI observations of nearby galaxies . I. The first list of the Karachentsev catalog
We present HI observations of the galaxies in the first list of theKarachentsev catalog of previously unknown nearby dwarf galaxies(Karachentseva & Karachentsev 1998). This survey covers all knownnearby galaxy groups within the Local Volume (i.e. within 10 Mpc) andtheir environment, that is about 25% of the total sky. A total of 257galaxies have been observed with a detection rate of 60%. We searched afrequency band corresponding to heliocentric radial velocities from -470km s-1 to ~ +4000 km s-1. Non-detections areeither due to limited coverage in radial velocity, confusion with LocalHI (mainly in the velocity range -140 km s-1 to +20 kms-1), or lack of sensitivity for very weak emission. 25% ofthe detected galaxies are located within the Local Volume. Thosegalaxies are dwarf galaxies judged by their optical linear diameter (1.4+/- 0.2 kpc on the average), their mean total HI mass (4.6107 Msun), and their observed linewidths (39 kms-1).
| Late-type dwarf irregular galaxies in the Virgo cluster - I. H alpha and red continuum data
We present H alpha and red continuum observations for a sample oflate-type low surface brightness (LSB) dwarf irregular galaxies,consisting of all the ImIV and V galaxies with m_B<= 17.2 in theVirgo cluster, and compare them with similar data for a representativesample of high surface brightness (HSB) dwarf irregular galaxies, alsoin the Virgo cluster. Line fluxes and equivalent widths are listed forindividual HII regions, and total H alpha emission is measured for theentire galaxy. Although significant line emission originates in the HIIregions that we have identified, it does not make up the entire H alphaoutput of all galaxies. For those objects in the LSB sample withHα emission, we find typical star formation rates (SFRs) from6.9x10^-3 to as high as 4.3x10^-2 M_solar yr^-1. This is, on average,one order of magnitude weaker than for HSB objects, although the SFRsoverlap. On average, ~2 HII regions are detected per LSB galaxy, for atotal of 38 HII regions among 17 galaxies with Hα emission. TheHII regions are smaller and fainter than in HSB galaxies in the sameVirgo cluster environment, have Hα line equivalent widths about 50per cent of those in HSBs, and cover similar fractions of the galaxies.When more than one HII region is present in a galaxy, we observe astrong intensity difference between the brightest and the secondbrightest HII regions. The line-emitting regions of LSB galaxies arepreferentially located at the periphery of the galaxy, while in HSBsthey tend to be central. The Hα line strength of an HII region iscorrelated with the red continuum light underneath the region; thisholds for both LSBs and HSBs. We do not identify fundamental differencesin the star formation properties of the LSB and HSB dwarf galaxies thatwe have studied, and we infer that these galaxies must be similar, withthe difference being the intensity of the present star formation burst.
| A list of new nearby dwarf galaxy candidates
To increase completeness of the distance limited sample of nearbygalaxies from the \cite[Kraan-Korteweg & Tammann (1979)]{Kra79}catalogue we undertook a search for small companions of larger knowngalaxies which have corrected radial velocities within 500 km/s. Basedprimarily on the POSS-II and ESO/SERC films we found 260 nearby dwarfgalaxy candidates with angular diameters aga0 .5 arcmin. More than 50%of the objects were revealed for the first time. As we suppose, asignificant part of them (about 30%) may really belong to the LocalVolume sample. Tables 1 and 2 also available in electronic form at CDSvia anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via\breakftp://cdsweb.u-strasbg.fr/Abstract.html
| The kinematics of the Virgo cluster revisited
The paper updates the velocity data of Virgo cluster galaxies andreconsiders the kinematic structure of the Virgo cluster. New velocitiesare given for 144 galaxies listed in the Virgo Cluster Catalog (VCC).Improved velocities are given for another 131 VCC galaxies. The Virgocluster is disentangled from its surrounding clouds of galaxies, and thelikely members of each of these clouds are listed. The velocitydistribution of dwarf elliptical cluster members is found to be highlyasymmetric. This phenomenon is interpreted as evidence for the imminentmerging of two subclusters in the core region, which points to thedynamical youth of the Virgo cluster. The mean heliocentric velocity ofthe Virgo cluster is estimated at 1050 +/- 35 km/s.
| H I detection survey of a complete magnitude-limited sample of dwarf irregular galaxies in the Virgo Cluster area
New single-beam Arecibo H I observations of 298 late-type galaxies inthe Virgo Cluster drawn mostly from the new catalog of Binggeli,Sandage, and Tammann (1985) are presented. Two hundred seventeen ofthese constitute a magnitude-limited 'complete sample' of such galaxies,types Sdm through Im and BCD. Sixty-one percent of this 'completesample' was detected, greatly enhancing the store of redshifts and H Imasses for such galaxies in the Virgo Cluster. For detected galaxies,heliocentric velocities, 50 percent profile widths, and single-beamfluxes are presented. For those that escaped detection, upper limits arecomputed to the flux appropriate to the redshift range (-600 to +3000km/s).
| Candidate Galaxies for Study of the Local Velocity Field and Distance Scale Using Space Telescope - Part Three - Galaxies in the Virgo Cluster Core
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1985AJ.....90.2006S&db_key=AST
| 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.
| A catalog of dwarf galaxies in Virgo
A catalog listing the location, apparent angular diameter, type,estimated central light concentration, and estimated brightness of 846dwarf galaxies in a 200-deg-sq region in Virgo is presented. Thegalaxies comprise 634 ellipticals, 137 IC-3475-type galaxies, 73 dwarfspirals and irregulars, and two objects which are jets of normalgalaxies, and were found on nine long-exposure IIIa-J-emulsion platesmade with the 1.2-m-Schmidt telescope at Palomar Observatory from 1971to 1976. Concordances to other catalogs, tables of additionalparameters, maps, graphs, and photographs are provided. The projecteddistributions of normal and dwarf galaxies and the dependence ofapparent luminosity on central light concentration are discussed. It isfound that dwarf ellipticals and IC-3475-type galaxies are probablemembers of the Virgo cluster, while dwarf spirals and possibly dwarfirregulars are not.
| Dwarf galaxies in the Virgo cluster.
Abstract image available at:http://adsabs.harvard.edu/cgi-bin/nph-bib_query?1956AJ.....61...69R&db_key=AST
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