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|Neutral Hydrogen Mapping of Virgo Cluster Blue Compact Dwarf Galaxies|
A new installment of neutral hydrogen mappings of blue compact dwarf(BCD) galaxies, as defined by optical morphology, in and near the VirgoCluster is presented. The primary motivation was to search for outlyingclouds of H I as potential interactive triggers of enhanced starformation, and therefore the mapped galaxies were selected for large H Imass, large optical diameter, and large velocity profile width.Approximately half the sample proved to have one or more small, lowcolumn density, star-free companion clouds, either detached or appearingas an appendage in our maps, at a resolution on the order of 4 kpc.Comparison is made with a sample of similarly mapped field BCD galaxiesdrawn from the literature; however, the Virgo Cluster sample of mappedBCDs is still too small for conclusive comparisons to be made. We found,on the one hand, little or no evidence for ram-pressure stripping nor,on the other, for extremely extended low column density H I envelopes.The H I rotation curves in most cases rise approximately linearly andslowly, as far out as we can trace the gas.
|An H I Survey of Actively Star-forming Dwarf Galaxies|
We present the results of H I 21 cm observations of 139 activelystar-forming dwarf galaxies obtained with the 305 m radio telescope atArecibo Observatory. Our sample consists of all objects cataloged inobjective-prism surveys for UV-excess or emission-line galaxiespublished prior to the start of the survey that have luminosities belowMB=-17.0 and that are located within the declination limitsof the Arecibo telescope. Galaxies from the Markarian, Michigan, Case,Wasilewski, Haro, and Zwicky lists are included. The sample spans a widerange of both H I gas content and star formation levels. A total of 122objects (88%) were detected; 82 galaxies have been observed for thefirst time in H I. The median velocity width for our sample is 88 kms-1, and the median H I gas mass is 3.0×108Msolar. In general, the sample galaxies are gas-rich, with anaverage MHI/LB=1.3 after correcting for theluminosity enhancement due to the starburst. The progenitors of many ofthe star-forming dwarfs have higher MHI/LB thantypically seen in samples of nearby ``normal'' galaxies, emphasizingtheir distinct nature.
|The UZC-SSRS2 Group Catalog|
We apply a friends-of-friends algorithm to the combined Updated ZwickyCatalog and Southern Sky Redshift Survey to construct a catalog of 1168groups of galaxies; 411 of these groups have five or more members withinthe redshift survey. The group catalog covers 4.69 sr, and all groupsexceed the number density contrast threshold, δρ/ρ=80. Wedemonstrate that the groups catalog is homogeneous across the twounderlying redshift surveys; the catalog of groups and their membersthus provides a basis for other statistical studies of the large-scaledistribution of groups and their physical properties. The medianphysical properties of the groups are similar to those for groupsderived from independent surveys, including the ESO Key Programme andthe Las Campanas Redshift Survey. We include tables of groups and theirmembers.
|The Morphologies of Dwarf Markarian Galaxies|
The morphologies of the 96 dwarf (M(B) -17m) galaxies in the Markariancatalog are determined from the digitized Schmidt plates obtained forthe construction of the Hubble Space Telescope Guide Star Catalog. Thefraction of double nucleus galaxies within the dwarf Markarian galaxiesis determined to be twice that found for all galaxies in the Markariancatalog. In addition to the 12 previously known cases, four definite andtwo probable galaxies with double nuclei are identified. The fraction ofdwarf Markarian galaxies with bright star forming regions is found to betwice that of Virgo cluster dwarf galaxies. No Elliptical galaxies arefound in the sample. Galaxies with blue compact dwarf and S0morphologies are more often found to contain unresolved regions of UVexcess emission. Dwarf Markarian galaxies with different morphologicalstructures and spectral classes are found to have similar FIRproperties.
|A Comparative Study of Star-forming and Quiescent Dwarf Galaxies|
We present the results from a comparative study of the atomic hydrogen(H I) and optical properties of a sample of 16 dwarf galaxies, chosen toinvestigate the effects of star formation on the properties of low-masssystems. The violent star formation bursts believed to occur in theselow-mass systems suggest a possible connection between the activelystar-forming blue compact dwarfs (BCDs), and the quiescent low surfacebrightness dwarfs (LSBDs). It has been suggested that LSBDs, uponundergoing a burst of star formation, will evolve into BCDs and thenback into LSBDs when the star formation slows or stops as the H I columndensity falls below the critical threshold necessary to support it. Wehave examined the location and kinematics of H I in eight BCDs and eightLSBDs of similar H I masses and a range of color indices to investigatethis ``evolutionary'' sequence. The starburst episodes in these low-massgalaxies should lead to (1) a dispersal/depletion of the H I seen in theeight LSB dwarfs and (2) more centrally concentrated and agitated H I inthe eight BCDs. The results of this project indicate that the quiescentLSBD galaxies have more diffuse H I distributions and often show aringlike structure, while the active galaxies have more highly centrallyconcentrated H I reservoirs. The bluer, more recently active systems ofboth types also have higher internal H I velocity dispersions,indicating that energy has been pumped into the interstellar medium ofthese galaxies. These observations are consistent with an evolutionaryscheme wherein the H I reservoirs in these galaxies take on differentcharacteristics depending upon their star formation histories.
|On the local radio luminosity function of galaxies. I. The Virgo cluster|
We cross-correlate the galaxies brighter than m_B=18 in the Virgocluster with the radio sources in the NVSS survey (1.4 GHz), resultingin 180 radio-optical identifications. We determine the radio luminosityfunction of the Virgo galaxies, separately for the early- andlate-types. Late-type galaxies develop radio sources with a probabilityproportional to their optical luminosity. In fact their radio/optical(R_B) distribution is gaussian, centered at log R_B ~ -0.5, i.e. theradio luminosity is ~ 0.3 of the optical one. The probability oflate-type galaxies to develop radio sources is almost independent oftheir detailed Hubble type, except for Sa (and S0+S0a) which are afactor of ~ 5 less frequent than later types at any R_B. Giantelliptical galaxies feed ``monster" radio sources with a probabilitystrongly increasing with mass. However the frequency of fainter radiosources is progressively less sensitive on the system mass. The faintestgiant E galaxies (M_B=-17) have a probability of feeding low power radiosources similar to that of dwarf E galaxies as faint as M_B=-13. Table~1is only available in electronic form at the CDS via anonymous ftp tocdsarc.u-strasbg.fr (22.214.171.124) or viahttp://cdsweb.u-strasbg.fr/Abstract.html
|A Complete Redshift Survey to the Zwicky Catalog Limit in a 2^h X 15 deg Region around 3C 273|
We compile 1113 redshifts (648 new measurements, 465 from theliterature) for Zwicky catalog galaxies in the region (-3.5d <= delta<= 8.5d, 11h5 <= alpha <= 13h5). We include redshifts for 114component objects in 78 Zwicky catalog multiplets. The redshift surveyin this region is 99.5% complete to the Zwicky catalog limit, m_Zw =15.7. It is 99.9% complete to m_Zw = 15.5, the CfA Redshift Survey(CfA2) magnitude limit. The survey region is adjacent to the northernportion of CfA2, overlaps the northernmost slice of the Las CampanasRedshift Survey, includes the southern extent of the Virgo Cluster, andis roughly centered on the QSO 3C 273. As in other portions of theZwicky catalog, bright and faint galaxies trace the same large-scalestructure.
|Total magnitude, radius, colour indices, colour gradients and photometric type of galaxies|
We present a catalogue of aperture photometry of galaxies, in UBVRI,assembled from three different origins: (i) an update of the catalogueof Buta et al. (1995) (ii) published photometric profiles and (iii)aperture photometry performed on CCD images. We explored different setsof growth curves to fit these data: (i) The Sersic law, (ii) The net ofgrowth curves used for the preparation of the RC3 and (iii) A linearinterpolation between the de Vaucouleurs (r(1/4) ) and exponential laws.Finally we adopted the latter solution. Fitting these growth curves, wederive (1) the total magnitude, (2) the effective radius, (3) the colourindices and (4) gradients and (5) the photometric type of 5169 galaxies.The photometric type is defined to statistically match the revisedmorphologic type and parametrizes the shape of the growth curve. It iscoded from -9, for very concentrated galaxies, to +10, for diffusegalaxies. Based in part on observations collected at the Haute-ProvenceObservatory.
|New aperture photometry for 217 galaxies in the Virgo and Fornax clusters.|
We present photo electric multi-aperture photometry in UBVRI of 171 and46 galaxies in the Virgo and Fornax clusters, respectively. Many of thegalaxies have not been observed in at least one of these passbandsbefore. We discuss the reduction and transformation into the Cousinsphotometric system as well as the extinction coefficients obtainedbetween 1990 and 1993.
|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.
|General study of group membership. II - Determination of nearby groups|
We present a whole sky catalog of nearby groups of galaxies taken fromthe Lyon-Meudon Extragalactic Database. From the 78,000 objects in thedatabase, we extracted a sample of 6392 galaxies, complete up to thelimiting apparent magnitude B0 = 14.0. Moreover, in order to considersolely the galaxies of the local universe, all the selected galaxieshave a known recession velocity smaller than 5500 km/s. Two methods wereused in group construction: a Huchra-Geller (1982) derived percolationmethod and a Tully (1980) derived hierarchical method. Each method gaveus one catalog. These were then compared and synthesized to obtain asingle catalog containing the most reliable groups. There are 485 groupsof a least three members in the final catalog.
|A catalog of Markarian galaxies|
A catalog of Markarian galaxies is presented which tabulates redshifts,spectral and morphological classifications, magnitudes, infrared andradio flux densities, and over 600 references to available datapublished before January 1, 1986. Redshifts are now available for 1228objects with strong ultraviolet continua, and follow-up spectroscopicand photometric observations of Markarian galaxies have providedclassifications of 115 Seyfert 1, 43 Seyfert 2, and 137 starburst and HII-type galaxies. After a description of the Markarian survey and thecurrent catalog, a summary of the general results obtained from the datais presented. A preliminary study of the infrared properties ofMarkarian galaxies as measured by IRAS reveals a number of interestingresults, including the existence of a sample of elliptical andlenticular galaxies with appreciable infrared emission.
|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.
|The structure of the Virgo cluster of galaxies|
A new detailed analysis of galaxies in the Virgo area shows that theconventional Virgo cluster comprises two different clouds of galaxies:the Virgo cluster I and the Southern cloud II by the definition proposedhere. Excluding the galaxies in the Southern cloud II, the Virgo clusterI centered at 12 h 27.6 m, +13 deg 07 arcmin (1950), has a mean radialvelocity of 980 + or - 60 km/s and there is no significant velocitydifference between elliptical-lenticular and spiral-irregular galaxiesin the Virgo cluster I. The Southern cloud II is centered at about 12 h25 m, +7 deg 30 arcmin (1950) and all types of galaxies in the cloud arediffusely distributed, while elliptical galaxies in the Virgo cluster Iare concentrated to the center. The mean radial velocity within a radiusof 3.5 deg of the Southern cloud II is +1240 + or - 80 km/s, which issignificantly higher than the mean velocity of the Virgo cluster I.
|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.
|Infall of galaxies into the Virgo cluster and some cosmological constraints|
The observed infall of galaxies in the Virgo Southern Extension towardthe Virgo Cluster is characterized by a family of mass models satisfyingthe requirement of an explanation of the Milky Way's motion with respectto the Virgo Cluster, in order to furnish constraints of cosmologicalinterest. If the age of the universe is 10-15 Gyr, there is a roughcoincidence of the mass required to explain the infall pattern ofgalaxies near the cluster, the mass needed to account for the motion ofthe Milky Way, and the mass implied for the central cluster by thevirial theorem, in which case most of the supercluster's mass mustreside in the Virgo Cluster. With the mass-age models and a census ofthe distribution of galaxies near the Virgo Cluster, it is possible toestimate the near-future accretion rate of galaxies into the centralcluster.
|Blue compact dwarf galaxies. I - Neutral hydrogen observations of 115 galaxies|
HI observations are reported for a sample of 115 blue compact dwarf(MB greater than approximately -18) galaxies or'extragalactic H II regions' chosen mostly from the objective prismsurveys of Markarian (1967-1974) and Haro (1956), with a few objectsfrom Zwicky (1971) and other investigators. Ninety-three galaxies aredetected. H I profiles, neutral hydrogen masses, total masses, and allavailable optical data are given for the 115 galaxies in a consistentand homogeneous system and in a useful format for statistical studies.The data are used in a companion paper to study the stochastic mode ofstar formation in galaxies.
|Galaxies with an ultraviolet continuum.|
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