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|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).
|The 3-D structure of the Coma-A 1367 supercluster: Optical spectroscopy of 102 galaxies|
Optical spectroscopy of 117 CGCG galaxies, 102 of which are projected inthe direction of the Coma-A 1367 supercluster, is reported. These newmeasurements, added to those found in the literature, bring to 1068 thenumber of CGCG galaxies in this region with available redshift, out of atotal of 1085 objects with m_p<= 15.7. We use these data to infer the3-D structure of the Coma supercluster. Based on observations obtainedwith the Loiano telescope belonging to the University of Bologna, Italy,and with the G. Haro telescope of the INAOE, Mexico.
|Radio-continuum survey of the Coma/A1367 supercluster. IV - 1.4 GHz observations of CGCG galaxies|
1.4 GHz radio-continuum observations of 148 CGCG galaxies in the Comasupercluster region were obtained with the VLA in C array configuration.Comparison with previous measurements at 0.6 GHz leads to an averagespectral index of 0.8. The structures of 29 galaxies in this regiondetermined with high-resolution VLA (A array) observations arepresented.
|A VLA 20 CM survey of poor groups of galaxies|
The paper reports on VLA 20 cm observations of an extensive sample ofgalaxies in 139 poor groups. These groups, composed of galaxies down tothe limit of the Zwicky et al. (CGCG) catalog, were chosen using apercolation algorithm set at a high surface-density threshold.Approximately 50 percent of the groups have measured redshifts. Thesegroups were surveyed using a 'snapshot' mode of the VLA with aresolution of about 13 arcsec. Analysis of the resulting radio andoptical properties reveals that the presence of a nearby companiongalaxy has an important role in generating radio emission in a galaxy.CCD observations of two radio-loud, disturbed galaxies with companionsare presented and are used to discuss models of radio-source production.Nine tailed radio galaxies are found in the poor groups, which is muchmore than had been expected from previous work on rich clusters and fromtheoretical models. The paper discusses previous statistical biases andproposes a method for bending head-tail sources in poor groups. From theconfinement of extended radio features associated with tailed sources,the presence of a substantial intracluster medium that should radiatesignificantly at soft-X-ray energies is predicted.
|The NGC 4005 group - A rotating system of galaxies?|
H I line observations with the Arecibo 305 m telescope were made of 23galaxies within a 7 square degree region centered on the NGC 4005 group,a system of galaxies located in Zw 127-10. Accurate radial velocitiesand direct mass estimates derived from the 21 cm line profiles of thegalaxies in this region are reported. A systematic trend in the radialvelocities is found along the major axis of the NGC 4005 group. Thiscorrelation between position and velocity is fitted to a simple linearregression relation with a slope significantly different from zero. Oneexplanation for this effect is that the NGC 4005 group is rotating witha period no longer than four billion yr. Other possible interpretationsof this systematic effect are discussed. The mass of the group isestimated by applying the harmonic law, the virial theorem, and theprojected mass method. The masses obtained from the three methods areall consistent.
|Radio continuum survey of the Coma/A1367 supercluster. I - 610 MHz observations of CGCG galaxies in four groups|
Radio continuum observations obtained with the Westerbork RadioSynthesis Telescope (WSRT) at 0.6 GHz of four groups of galaxies in theComa/A1367 supercluster area are presented. Ninety-nine CGCG galaxieswere surveyed, yielding the detection of 21 objects. A wide-angle-tailradio galaxy, NGC 4061, in the NGC 4065 group is found. Analysis of thissource suggests a relatively low value (n(e) T approximately 1000 per cucm K) for the intracluster gas pressure in this group.
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