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|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.
|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.
|Galaxy coordinates. II. Accurate equatorial coordinates for 17298 galaxies|
Using images of the Digitized Sky Survey we measured coodinates for17298 galaxies having poorly defined coordinates. As a control, wemeasured with the same method 1522 galaxies having accurate coordinates.The comparison with our own measurements shows that the accuracy of themethod is about 6 arcsec on each axis (RA and DEC).
|Molecular gas in polar-ring galaxies|
We present CO J=1-->0 observations (lambda=2.6 mm) of 10 polar-ringgalaxies, chosen from the Polar Ring Catalogue; we infer masses of H_2ranging from 7x10^7 to 2x10^10 Msolar, with an average of about 1x10^9Msolar. These H_2 masses are greater than the average molecular mass ofan early-type galaxy; we previously found similar results for a sampleof minor-axis dust-lane ellipticals. In the cases where we can estimatethe gas mass in the polar ring, including the H i masses fromliterature, they are high enough to allow self-gravitation to stabilizethe rings. This means that the ages of the rings may be >=1 Gyr.Indeed, the gas masses are often greater than those of most dwarfgalaxies: this would make it unlikely that the polar rings result fromthe recent accretion of a single gas-rich dwarf. A survey of the fieldsaround our sample galaxies shows in all but one case the presence of atleast one companion with either a similar redshift or similar bluemagnitude; these companions are close enough to have encountered thepolar-ring galaxy in <1 Gyr. The companion galaxies may be the sourceof the detected gas, through tidal stripping.
|A redshift survey toward a proposed void of galaxies suggested by the distribution of Abell clusters|
A program of redshift measurements was carried out in a region of thesky in which a relative under-density of Abell clusters had been used toinfer the presence of a large (diameter about 40/h Mpc) void in thegeneral galaxy distribution. The purpose of this study was toinvestigate whether the large-scale distribution of galaxies is tracedby the distribution of rich clusters. Redshifts are presented for 308galaxies in the Zwicky Catalog in a 234 square degree region centered onR.A. about 2h, Decl. about 12 deg of which 229 have been newly measured.These data reveal a pattern of filamentary structure alternating withvoids of characteristic diameter about 25-30/h Mpc, throughout thevolume sampled. While the redshift data reveal an underdensity in thedistribution of galaxies in the general region suggested by the Abellcluster distribution, they do not support the existence there of a 40/hMpc diameter void.
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