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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 morphological segregation of galaxies in clusters. II. The properties of galaxies in the Coma cluster.|
We have looked for differences in the galaxy properties along the Hubblesequence and for the dependence of these properties on the environment,in an absolute magnitude complete sample of 187 galaxies in the Comacluster. The morphological type of all galaxies was determined from ourown high resolution data. We also compared this sample with otherpublished complete samples of galaxies in the Perseus and Virgo clustersand in the local field. Ellipticals and lenticulars are highlyhomogeneous in all their internal photometric properties. These galaxiesare well described just by their morphological type and luminosity,regardless of the environment. On the other hand, some of the externalproperties of these galaxies and of their subclasses differ markedly.Then, for early-type galaxies, the environment determines the spacedensity of each type but not the internal properties of the type, whichare the same in all environments. Spirals form a heterogeneous class ofobjects whose photometric properties depend on one extra parameter. As aresult, spirals that are blue in the optical also have blueultraviolet-optical colors, higher mean surface brightness (or smallerradii) for their magnitude, strongly avoid the cluster center and havehigh velocities relative to the cluster center. The spatial distributionof spirals as a whole class is uniform. For spirals, therefore, theenvironment does not determine the space density, which is the same inall environments, but strongly affects the internal galaxy properties.The galaxies in Coma, as in Perseus, are segregated primarily withrespect to the supercluster main direction, thus providing a newinterpretation of the morphology-radius and morphology-densityrelations. Finally, the NGC 4839 group is richer in early-type galaxiesthan other regions at the same distance from the cluster center, showingthat the morphological segregation could be a useful tool fordiscriminating fortuitous alignments from real groups.
|Radial Velocities of Ring-Shaped Galaxies - Part Two|
|A Green Bank Sky Survey in Search of Radio Sources at 1400 MHz. III. Positions and Flux Densities of the GB Radio Sources|
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