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On the Neutral Gas Content and Environment of NGC 3109 and the Antlia Dwarf Galaxy
As part of a continuing survey of nearby galaxies, we have mapped theneutral gas content of the low surface brightness Magellanic-type galaxyNGC 3109 and its environment, including the Antlia dwarf galaxy, atunprecedented velocity resolution and brightness sensitivity. The H Imass of NGC 3109 is measured to be 3.8+/-0.5×108Msolar. A substantial warp in the disk of NGC 3109 isdetected in the H I emission image in the form of an extended lowsurface brightness feature. We report a positive detection in H I of thenearby Antlia dwarf galaxy and measure its total neutral gas mass to be6.8+/-1.4×105 Msolar. We show the warp inNGC 3109 to lie at exactly the same radial velocity as the gas in theAntlia dwarf galaxy and speculate that Antlia disturbed the disk of NGC3109 during a mild encounter ~1 Gyr in the past. H I data for a furthereight galaxies detected in the background are presented.
| 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.
| The Catalog of Southern Ringed Galaxies
The Catalog of Southern Ringed Galaxies (CSRG) is a comprehensivecompilation of diameters, axis ratios, relative bar position angles, andmorphologies of inner and outer rings, pseudorings, and lenses in 3692galaxies south of declination -17 deg. The purpose of the catalog is toevaluate the idea that these ring phenomena are related to orbitalresonances with a bar or oval in galaxy potentials. The catalog is basedon visual inspection of most of the 606 fields of the Science ResearchCouncil (SRC) IIIa-J southern sky survey, with the ESO-B, ESO-R, andPalomar Sky surveys used as auxiliaries when needed for overexposed coreregions. The catalog is most complete for SRC fields 1-303 (mostly southof declination -42 deg). In addition to ringed galaxies, a list of 859mostly nonringed galaxies intended for comparison with other catalogs isprovided. Other findings from the CSRG that are not based on statisticsare the identification of intrinsic bar/ring misalignment; bars whichunderfill inner rings; dimpling of R'1pseudorings; pointy, rectangular, or hexagonal inner or outer ringshapes; a peculiar polar-ring-related system; and other extreme examplesof spiral structure and ring morphology.
| An HI survey of late-type galaxies in the Southern Hemisphere. I - The SGC sample
The present H I survey of Southern Hemisphere late-type galaxies wascompleted at the Nancay radio telescope between 1985 and 1988 and coverslarge galaxies selected from the Corwin et al. (1985) SGC catalog. Ofthe 311 galaxies observed, only 245 were detected due to the very lowsurface brightness of the Magellanic irregulars. These determinationsare conceived as useful for the establishment of distance criteria forlate-type galaxies. A histogram is presented of the velocities for thedetected galaxies vs morphological stages; attention is given toindividual spectra for 242 galaxies in the sample.
| The masses of twenty-eight active galactic nuclei
A statistical analysis of the X-ray time variability and luminosity of28 quasars and Seyfert galaxies is presented. For the case of a thickaccretion disk, the variation of the ratio between total luminosity andEddington luminosity is found. The mass of the central body and the sizeof the emission region are obtained. The dynamical masses based on theH-beta and forbidden O III lines are calculated for comparison. There isgood agreement between the masses derived by the two methods.
| Analysis of X-ray time variability in active galactic nuclei.
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| Southern Galaxy Catalogue.
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