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|HI in NGC 5433 and its environment: high-latitude emission in a small galaxy group|
We present HI synthesis maps of the edge-on starburst NGC 5433 and itsenvironment, obtained with the Very Large Array in its C and Dconfigurations. The observations and spectral model residuals of themain disc emission in NGC 5433 reveal three extraplanar features. Weassociate two of these features with coherent extraplanar extensionsacross multiple spectral channels in our data, including a complete loopin position-velocity space. Interpreting the latter as an expandingshell we derive a corresponding input energy of 2 ×1054 erg, comparable to that for the largest supershellsfound in the Galaxy and those in other edge-on systems. NGC 5433 is in aricher environment than previously thought. We confirm that KUG 1359+326is a physical companion to NGC 5433 and find two new faint companions,both with Minnesota Automated Plate Scanner identifications, which welabel SIS-1 and SIS-2. Including the more distant IC 4357, NGC 5433 isthe dominant member of a group of at least five galaxies, spanning over750 kpc in a filamentary structure. A variety of evidence suggests thatinteractions are occurring in this group. While a number of underlyingmechanisms are consistent with the morphology of the high-latitudefeatures in NGC 5433, we argue that environmental effects may play arole in their generation.
|The second Kiso Survey for ultraviolet-excess galaxies. II.|
|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.
|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.
|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.
|The velocity-distance relation for galaxies on a bubble|
The characteristic diameter of the most prominent void in the redshiftsurvey of de Lapparent et al. (1986) is measured. Distances and peculiarvelocities to individual galaxies are derived, and it is shown that thevoid is approximately a 'Hubble Bubble' in which the near and far edgesare separating with the general expansion of the universe. At the 3sigma level, infall toward the Coma cluster is detected for a portion ofthe bubble wall. Limits on the net outflow from the void and infall intoComa are used to estimate Omega.
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