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Публикации по объекту
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.
| Investigation of galaxies in and near the cluster A1185
Results of optical, radio, and submillimeter studies of the nearbygalaxy cluster A1185 are presented. Coordinates have been obtained for115 galaxies that are either cluster members or field galaxies in thedirection of A1185. Radio spectra for a number of galaxies in thiscluster have been derived using observations on the RATAN-600 radiotelescope at 2.7, 3.9, 7.6, 13, and 31 cm, together with data publishedin other studies. At the cluster center, some of the galaxies haveeither flat or inverted spectra. The vast majority of the galaxiesdisplay a uniform brightness distribution; i.e., they do not show anysigns of structure. Sixty-four percent of the galaxies are elliptical,and 31% are spherical. The total number of blue galaxies is 22%.
| Arcsecond Positions of UGC Galaxies
We present accurate B1950 and J2000 positions for all confirmed galaxiesin the Uppsala General Catalog (UGC). The positions were measuredvisually from Digitized Sky Survey images with rms uncertaintiesσ<=[(1.2")2+(θ/100)2]1/2,where θ is the major-axis diameter. We compared each galaxymeasured with the original UGC description to ensure high reliability.The full position list is available in the electronic version only.
| The Dynamics of Poor Systems of Galaxies
We assemble and observe a sample of poor galaxy systems that is suitablefor testing N-body simulations of hierarchical clustering and otherdynamical halo models. We (1) determine the parameters of the densityprofile rho(r) and the velocity dispersion profile sigma_p(R), (2)separate emission-line galaxies from absorption-line galaxies, examiningthe model parameters and as a function of spectroscopic type, and (3)for the best-behaved subsample, constrain the velocity anisotropyparameter, beta, which determines the shapes of the galaxy orbits. Oursample consists of 20 systems, 12 of which have extended X-ray emissionin the ROSAT All-Sky Survey. We measure the 877 optical spectra ofgalaxies brighter than m_R~15.4 within 1.5 h^-1 Mpc of the systemcenters (we take H_0=100 h km s^-1 Mpc^-1). Thus, we sample the systemmembership to a radius typically three times larger than other recentoptical group surveys. The average system population is 30 galaxies, andthe average line-of-sight velocity dispersion is ~300 km s^-1. TheNavarro, Frenk, & White universal profile and the Hernquist modelboth provide good descriptions of the spatial data. In most cases anisothermal sphere is ruled out. Systems with declining sigma_p(R) arewell-matched by theoretical profiles in which the star-forming galaxieshave predominantly radial orbits (beta>0) many of these galaxies areprobably falling in for the first time. There is significant evidencefor spatial segregation of the spectroscopic classes regardless ofsigma_p(R).
| Properties of nearby clusters of galaxies. III. A 76, A 157, A 407, A 505, A 671, A 779, A 1700, A 2028, A 2040, A 2052 A 2063, A 2065, A 2593, A 2657, A 2670
We present F band photometry, from digitized 48-inch Palomar plates, of2818 galaxies brighter than m_3+3 in 15 Abell clusters. For each galaxy,absolute coordinates, magnitude, size, ellipticity and orientation aregiven. For each cluster we provide finding charts and contour maps ofthe galaxy surface density. The absolute coordinates of the galaxies ofother 8 clusters presented in the first paper of this series are alsoincluded.
| The Lumpy Cluster Abell 1185
Abell 1185, a richness class 1 cluster of galaxies (cz = 9800 km s^-1^),has kinematic and x-ray substructure. We measure 39 new velocities inits field, bringing the known cluster population to 82 galaxies within1.4 h^-1^ Mpc of the cluster center. The sample has a depth of m_R_ ~15.8, and no substantial spatial bias. In addition to the optical datawe reanalyze a deep (11459 s) Einstein x-ray observation. Clumps in thevelocity distribution of A1185 are localized on the sky. The Dressler-Shectman test confirms the existence of subclumps with >99%confidence. X-ray emission from the cluster also appears complex;contributions from individual galaxies within A1185 are detectable. Thebrightest unresolved x-ray source coincides with an elliptical galaxywhich contains an active LINER nucleus. Throughout the paper we defineH_0_= 100 h km s^-1^ Mpc^- -1^, and unless otherwise indicated, weassume h = 1.
| 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 positions and 327 MHz flux-densities of UGC galaxies in selected Westerbork fields
The study presents accurate optical positions of 421 UGC galaxies whichare used to search for 30 92-cm WSRT fields observed for emission fromthese galaxies. Good 92-cm flux densities were obtained for 140galaxies, marginal flux densities for 71 galaxies, and upper limits for210 galaxies. For 35 galaxies, spectral indices in the decimeterwavelength range are determined. The mean spectral index for spiralgalaxies (0.72 +/- 0.03) is very similar to that of elliptical galaxies(0.64 +/- 0.10). The four multiple systems in the sample have a muchflatter spectral index (-0.21 +/- 0.07), from which the presence of asignificant thermal component in their total radio emission issuggested. Comparison with IRAS results show that about half of thegalaxies detected at radio wavelengths are detected in the FIR. It isproposed that some spiral galaxies are anomalously weak in the IR ascompared with their radio brightness.
| Properties of nearby clusters of galaxies. I - A 195, A 465, A 1185, A 1213, A 1413, A 1775, A 2319 and A 2597
A study of the properties of nearby clusters of galaxies has beenundertaken. This paper describes the data, derived from automated scansof photographic plates. Different methods for the evaluation of clustercenter, ellipticity, and orientation are compared, and errors areestimated by Monte Carlo simulations. Results are presented of theanalysis of 1256 galaxies brighter than m3 + 3 in eight Abell clusters.It is found that different methods give consistent estimates ofellipticity and orientation, provided the radial dependence of thesequantities is taken into account. It is also found that centraldensities are consistent with isothermal fits if the center is selectedas the baricenter of the cluster. For each galaxy, rectangularcoordinates, magnitude, size, ellipticity, and orientation are given.Each cluster is provided with identification maps and contour maps ofgalaxy surface density.
| A dynamical analysis of twelve clusters of galaxies
Four-hundred-twenty-eight new redshift measurements for galaxies in thevicinity of 12 Abell clusters are presented. The data are supplementedby previously published data with 3 deg of each cluster center. Thecluster selection, the variety of telescopes and instrumentation used toobtain the galaxy redshifts, and the available X-ray observations arediscussed. Each cluster is exmained in some detail, with the emphasisplaced on the nature of the observed velocity distributions. Robust andresistant estimators of the velocity location and scale are applied inorder to quantify these distributions. The offset in velocity space ofthe dominant galaxy in each cluster or subcluster is considered withrespect to the central location in the velocity space of the cluster asa whole, and the physical implications of significant offsets found inseveral clusters are discussed. Dynamical estimates of the masses ofclusters and/or subclusters are obtained; for clearly bimodal systems,two-body models are employed to specify their likely dynamical state.
| Periodicities in galaxy redshifts
Using new data for unassociated galaxies with wide H I profiles andvalues of period and solar motion predicted by Tifft and Cocke (1984), aperiodicity has been found which is significant at the conventional 5percent level. Together with Tifft's work on galaxy pairs and smallgroups, this result appears to provide evidence in favor of thehypothesis that measured galaxy redshifts occur in steps of a littlemore than 72 km/s or a simple multiple of this period.
| Groups of galaxies in the Center for Astrophysics redshift survey
By applying the Huchra and Geller (1982) objective group identificationalgorithm to the Center for Astrophysics' redshift survey, a catalog of128 groups with three or more members is extracted, and 92 of these areused as a statistical sample. A comparison of the distribution of groupcenters with the distribution of all galaxies in the survey indicatesqualitatively that groups trace the large-scale structure of the region.The physical properties of groups may be related to the details oflarge-scale structure, and it is concluded that differences among groupcatalogs may be due to the properties of large-scale structures andtheir location relative to the survey limits.
| A study of the large-scale structure in the distribution of galaxies in a region centered about the Cancer cluster. III - Further observational results
Further observational results are presented from a study of thelarge-scale structure in the distribution of galaxies in anapproximately 4000 sq deg region nominally centered about the Cancercluster. The criteria used in defining the galaxy sample and theobservational methods used in its study are reviewed. The H I spectraand the associated measured parameters and derived properties for the134 sample galaxies are presented.
| Radio emission in isolated and cluster spiral galaxies
In the 2380-MHz continuum radio observations presented for two samplesof spiral galaxies observed with the NAIC Arecibo 305-m telescope, thesamples have been chosen in such a way that they differ markedly in thedensity of surrounding galaxies. One sample includes exclusivelygalaxies from the Karachentseva (1973) Catalog of Isolated Galaxies, theother only galaxies found within one Abell radius from the center ofnearby Abell clusters. The goal is to obtain a comparison of the radioproperties of the galaxies in these two samples, to ascertain whetherenvironmental processes affect significantly their radio emissivity.Above a threshold of five times the rms confusion, 7 percent of thecluster galaxies and 5 percent of the isolated ones are detected. Withthe caution required by the effects of confusion on the single-dishobservations, no significant differences are found in theradio-continuum properties of these two samples.
| 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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