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|Nearby Optical Galaxies: Selection of the Sample and Identification of Groups|
In this paper we describe the Nearby Optical Galaxy (NOG) sample, whichis a complete, distance-limited (cz<=6000 km s-1) andmagnitude-limited (B<=14) sample of ~7000 optical galaxies. Thesample covers 2/3 (8.27 sr) of the sky (|b|>20deg) andappears to have a good completeness in redshift (97%). We select thesample on the basis of homogenized corrected total blue magnitudes inorder to minimize systematic effects in galaxy sampling. We identify thegroups in this sample by means of both the hierarchical and thepercolation ``friends-of-friends'' methods. The resulting catalogs ofloose groups appear to be similar and are among the largest catalogs ofgroups currently available. Most of the NOG galaxies (~60%) are found tobe members of galaxy pairs (~580 pairs for a total of ~15% of objects)or groups with at least three members (~500 groups for a total of ~45%of objects). About 40% of galaxies are left ungrouped (field galaxies).We illustrate the main features of the NOG galaxy distribution. Comparedto previous optical and IRAS galaxy samples, the NOG provides a densersampling of the galaxy distribution in the nearby universe. Given itslarge sky coverage, the identification of groups, and its high-densitysampling, the NOG is suited to the analysis of the galaxy density fieldof the nearby universe, especially on small scales.
|A Dynamical Study of Galaxies in the Hickson Compact Groups|
To investigate dynamical properties of spiral galaxies in the Hicksoncompact groups (HCGs), we present rotation curves of 30 galaxies in 20HCGs. We found as follows: (1) There is no significant relation betweendynamical peculiarity and morphological peculiarity in HCG spiralgalaxies. (2) There is no significant relation between the dynamicalproperties and the frequency distribution of nuclear activities in HCGspiral galaxies. (3) There are no significant correlations between thedynamical properties of HCG spiral galaxies and any group properties(i.e., size, velocity dispersion, galaxy number density, and crossingtime). (4) Asymmetric and peculiar rotation curves are more frequentlyseen in the HCG spiral galaxies than in field spiral galaxies or incluster ones. However, this tendency is more obviously seen in late-typeHCG spiral galaxies. These results suggest that the dynamical propertiesof HCG spiral galaxies do not strongly correlate with the morphology,the nuclear activity, and the group properties. Our results also suggestthat more frequent galaxy collisions occur in the HCGs than in the fieldand in the clusters.
|The intra-cluster medium influence on spiral galaxies|
We made a detailed analysis of the sample of 39 cluster spiral galaxiesof various types observed at Hα wavelength by Amram et al. (1992to 1996), with a scanning Fabry-Perot. We plotted the outer gradient oftheir rotation curves as a function of the deprojected cluster-centricdistance. The rotation curves of late type galaxies markedly rise farfrom the cluster center. This suggests evolutionary effects, since earlytypes show no special trend. We suggest that the evolution processwithin a cluster leads late type galaxies to exhibit flatter curves whenthey get closer to the center, on their way to evolving into early typegalaxies.
|Fabry-Perot observations of the ionized gas in NGC 3938|
The nearly face-on spiral galaxy NGC 3938 has been observed in theH_alpha line with the TAURUS II Fabry-Perot interferometer at theWilliam Herschel Telescope in order to study the kinematics of theionized gas. We are able to construct intensity, velocity and velocitydispersion maps for this galaxy. The rotation curve of the galaxy iscalculated up to 4.5 radial scale lengths from the galactic centre. Theresidual velocity field shows very small values with no systematicpattern. The mean velocity dispersion is approximately constant withradius at about 11 km s(-1) as previously reported for the neutral andmolecular gas. We have also studied the relation between intensity andvelocity dispersion for the ionized gas. We have found that thisdistribution is compatible with a turbulent gas relaxing to a Kolmogorovtype turbulence as the stationary regime. The average dispersion varieswith intensity as sigma ~ I(1/8) although it becomes much steeper athigher intensities, for which the dispersion is kept almost constant ata value of about 19 km s(-1) . Based on observations made with theWilliam Herschel Telescope operated on the island of La Palma by theIsaac Newton Group in the Spanish Observatorio del Roque de losMuchachos of the Instituto de Astrofisica de Canarias
|A catalogue of spatially resolved kinematics of galaxies: Bibliography|
We present a catalogue of galaxies for which spatially resolved data ontheir internal kinematics have been published; there is no a priorirestriction regarding their morphological type. The catalogue lists thereferences to the articles where the data are published, as well as acoded description of these data: observed emission or absorption lines,velocity or velocity dispersion, radial profile or 2D field, positionangle. Tables 1, 2, and 3 are proposed in electronic form only, and areavailable from the CDS, via anonymous ftp to cdsarc.u-strasbg.fr (to22.214.171.124) or via http://cdsweb.u-strasbg.fr/Abstract.html
|Structure and kinematics of galaxy clusters. I. The redshift catalogue.|
An extensive redshift survey has been conducted on a sample of 15 nearby(0.01<~z<~0.05) clusters of galaxies. A total number of 860redshifts were determined by fitting of emission-lines and/orcross-correlation techniques. Of this sample, 735 galaxies are within0.2-0.8Mpc (H_0_=50km/s/Mpc) of the center of clusters. Approximatemorphological types are available for most of the galaxies. A comparisonof the present redshifts with published data allows an extensive erroranalysis. The agreement is excellent with the most modern data, showinga zero point error of 5km/s and an overall consistency of themeasurements and their uncertainties. We estimate our redshifts to havemean random errors around 30km/s. A population analysis of the clusterswill be given in a forthcoming paper.
|The rotation curve of the cluster galaxy DC 1842-62 No. 24 does not decrease.|
Whitmore, Forbes & Rubin (1988) claimed a good correlation betweenslope of rotation curves and location within a cluster, in the sensethat inner galaxies tend to have falling rotation curves, while outerand field galaxies tend to have flat or rising rotation curves. Amram etal (1993, 1995b) did not confirm these correlations. Nevertheless, thelack of very inner galaxies in our sample did not allow us to concludeif environmental effects are important within a very small distance fromthe cluster center. The galaxy DC 1842-62 #24 presented both the mostdecreasing rotation curve and the closest location to the cluster centerin Whitmore et al.'s sample (1988), and thus was a crucial case in thestudy of rotation curve behaviour in the very inner part of a cluster.From Perot-Fabry observations, we definitively find a non-decreasingrotation curve for this galaxy. A two-component mass model (disk plushalo) rules out any decrease of the rotation curve and indicates thatluminous matter is dominant.
|The Catalog of Southern Ringed Galaxies|
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
|Hα velocity fields and rotation curves of galaxies in clusters. III. Nine galaxies in DC 1842-63.|
Hα maps (continuum and line), velocity contour maps and rotationcurves are presented for 9 galaxies in the Southern cluster DC 1842-63.These data have been obtained from two-dimensional Hα observationsat the 3.60-m ESO Telescope equipped with CIGALE, a scanning Fabry-Perotinterferometer. They complete the set of 36 galaxies already observedwith the same kind of instrumentation at CFHT (Amram et al. 1992, 1994).
|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.
|Dynamics of clusters of galaxies with central dominant galaxies. I - Galaxy redshifts|
Optical redshifts are presented for a sample of 638 galaxies in thefields of the clusters Abell 85, DC 0107-46, Abell 496, Abell 2052, andDC 1842-63. The velocity histograms and wedge diagrams show evidence fora foreground sheet of galaxies in Abell 85 and background sheets ofgalaxies in DC 0107-46 and Abell 2052. The foreground group projectedagainst the center of Abell 85 found by Beers et al. (1991) isconfirmed. No evidence of substructure was found in Abell 496, Abell2052, and DC 1842-63. The clusters have global velocity dispersionsranging from 551 km/s for DC 1842-63 to 714 km/s for A496, and flatdispersion profiles. Mass estimates using the virial theorem and theprojected mass method range from 2.3 x 10 exp 14 solar masses for DC0107-46 to 1.1 x 10 exp 15 solar masses for A85.
|The supergalactic plane redshift survey|
Redshift measurements, about 1000 of which are new, are presented for1314 galaxies in a survey toward the apex of the large-scale streamingflow for ellipticals. The velocity histogram shows that the excess ingalaxy number counts in this area is due to a substantial concentrationof galaxies with discrete peaks at V about 3000 km/s and V about 4500km/s. After correction for the sampling function, the centroid of thedensity distribution is found to be near V about 4500 km/s.Normalization to the more extensive SSRS survey, which was selected bythe same criteria, shows that the region studied contains a considerableoverdensity of galaxies from 2000 to 6000 km/s. This result is in goodagreement with the 'great attractor' model suggested by Lynden-Bell etal. (1988) which attributes the peculiar motions of elliptical galaxiesover a large region of space to an extensive mass overdensity whichincludes the Hydra-Centaurus and Pavo-Indus superclusters. The centroidof the density enhancement is also consistent with new data by Dresslerand Faber (1990) of peculiar motions of elliptical and spiral galaxies,both of which show a zero crossing of the Hubble line at approximately4500-5000 km/s.
|Multicolour photometry of the cluster of galaxies Sersic 129-01|
Photometry is presented of 907 galaxies brighter that b(26.25) = 20.5 ina 1.83 x 1.83 deg area centered on the southern cluster Sersic 129-01 inthe u, b, r and i bands. The slopes and zero-points of thecolor-absolute magnitude diagrams agree well with other clustersincluding Coma and the rich cluster Shapley 8 suggesting they areindependent of cluster environment. The (u-b) against (b-i) diagramdistinguishes well between morphological types. The reddening obtainedby a number of methods disagrees with that of Griersmith (1982). A massof 7.4 x 10 to the 13th solar masses is found for the ellipticaldominated component of the cluster and (M/L)b = 59.
|Photometric properties of galaxies in the cluster DC 1842-63|
Results are presented from photometric and kinematic observations of thecluster DC 1842-63, including total magnitudes for 174 galaxies, surfacephotometry and bulge-to-disk ratios for 31 galaxies, and redshiftsmeasurements for 20 galaxies. The mean cluster velocity is found to be4437 + or - 78 km/s with a cluster velocity dispersion of 507 km/s. TheX-ray luminosity of the cluster is shown to be 3.0 X 10 to the 43rderg/s in the 0.5 and 4.5 keV band.
|Rotation curves for spiral galaxies in clusters and in the field|
This paper compares the H-alpha emission-line rotation curves and the HI rotation curves of spiral galaxies in clusters with their counterpartsin the field, using the following three criteria: the inner and outervelocity gradients, the mass-to-light ratio (M/L) gradients, and theBurstein's mass-type methodology. Results show a good correlationbetween the outer gradient of the rotation curve and the galaxy'sdistance from the center of the cluster; namely, the inner galaxies tendto have falling rotation curves, while the outer galaxies and fieldgalaxies tend to have flat or rising rotation curves. In addition, acorrelation was found between the M/L gradient across a galaxy and thegalaxy's position in the cluster, with the outer galaxies having steeperM/L gradients. Contrary to earlier reports, the mass types for fieldspirals were found to be a function of both Hubble-type and luminosity.These correlations indicate that the inner cluster environment can stripaway some fraction of the mass in the outer halo of a spiral galaxy.
|Rotation curves for spiral galaxies in clusters. II - Variations as a function of cluster position|
Inner and outer velocity gradients, residuals from synthetic rotationcurves for field spirals, and M/L gradients are used to study therotation curves of spiral galaxies. A good correlation is found betweenthe outer gradient of the rotation curve and the galaxy's distance fromthe cluster center, with a similar effect noted in the residuals betweenthe observed and synthetic rotation curves. A correlation is also shownto exist between the M/L gradient across a galaxy and the galaxy'sposition in the cluster. The results suggest that the inner clusterenvironment may strip away some fraction of the mass in the outer haloof a spiral galaxy or may not allow the halo to form.
|Rotation curves for spiral galaxies in clusters. I - Data, global properties, and a comparison with field galaxies|
Rotational velocities have been obtained for 21 galaxies in the largespiral-rich clusters Cancer, Hercules, Peg I, and DC 1842-63. It isnoted that the larger, brighter, more massive spirals which are rare inthe field are absent in the cluster spirals. Falling rotation curveshave been found. The amplitudes of the rotation curves for the nine Saand Sb galaxies considered are shown to be lower than those of theirfield counterparts. The results indicate that galaxies which are H Ideficient have rotation curves which are most depressed in comparisonwith field spirals of equivalent Hubble type and luminosity.
|Is the distribution of mass within spiral galaxies a function of galaxy environment?|
Rotation curves have been derived for 20 spiral galaxies that are knownto be members of large clusters. The forms of mass distributions forthese galaxies are compared to those previously determined for 60relatively isolated spiral galaxies. Hubble types Sa, Sb, and Sc areequally represented in field and cluster samples. Yet, cluster galaxieshave statistically different forms of rotation curves, and hencedifferent forms of mass distributions, than field galaxies. Indeed, theevidence suggests that the form of mass distribution for a spiral galaxyis more a function of environment than of Hubble type.
|A catalog of morphological types in 55 rich clusters of galaxies|
Data are presented from a study of 55 rich clusters of galaxies. Thedata include positions, morphological types, estimated total magnitudes,bulge sizes, and ellipticities for about 6000 galaxies, as determinedfrom high scale photographic plates. Data reduction procedures aredescribed, and a brief analysis of cluster richness, which indicatesthat Abell richness classes are only rough indicators of total clustermembership, is included.
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