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Dwarf and Normal Spiral Galaxies: are they Self-Similar?
The investigation presented here was focused on clarifying the existenceof dwarf spiral galaxies as a separate group from classical spirals.First, a list of spiral galaxies with small sizes was obtained.Information on colors, luminosities, morphologies and chemical contentwas searched for in the literature for these galaxies. Using thisinformation, it can be concluded that dwarf spirals are not likely to bethe tail of the distribution of classical galaxies. On the contrary,significant differences in some of the most important properties ofspiral galaxies, such as the metallicity gradient and the bar frecuency,were found. In any case, further and more accurate observations areneeded for a definitive answer.
| Neutral Gas Distribution and Kinematics of the Nearly Face-on Spiral Galaxy NGC 1232
We have analyzed high velocity resolution H I synthesis observations ofthe nearly face-on Sc galaxy NGC 1232. The neutral gas distributionextends well beyond the optical extent of the galaxy. As expected, localpeaks in the H I column density are associated with the spiral arms.Further, the H I column density drops precipitously near the center ofthe galaxy. Closed contours in the velocity field suggest either thatthe system is warped or that the rotation curve declines. The velocitydispersion is approximately constant throughout the system, with amedian value of 9.9+/-1.8 km s-1. When corrected forrotational broadening, there is no indication of a radial trend in theneutral gas velocity dispersion in this galaxy.
| Catalogue of HI maps of galaxies. I.
A catalogue is presented of galaxies having large-scale observations inthe HI line. This catalogue collects from the literature the informationthat characterizes the observations in the 21-cm line and the way thatthese data were presented by means of maps, graphics and tables, forshowing the distribution and kinematics of the gas. It containsfurthermore a measure of the HI extension that is detected at the levelof the maximum sensitivity reached in the observations. This catalogueis intended as a guide for references on the HI maps published in theliterature from 1953 to 1995 and is the basis for the analysis of thedata presented in Paper II. The catalogue is only available inelectronic form at the CDS via anonymous ftp 130.79.128.5 orhttp://cdsweb.u-strasbg.fr/Abstract.html
| 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 luminosity index as a distance indicator and the structure of the Virgo cluster
The usefulness of the luminosity index as a distance indicator isevaluated. The magnitude-luminosity index correlation in the VirgoCluster observed by Sandage et al. (1985) (SBT) and the correlationdetected by de Vaucouleurs et al., (1976) (VVC) are analyzed andcompared. The SBT data indicate that the luminosity index is not a gooddistance indicator due to a large dispersion (1.0 mag) of apparentmagnitudes. Examination of the data reveals that SBT obtained a largedispersion due to the inclusion of galaxies outside the Virgo Clusterproper, and identification, classification, and systematic errors in thedata. Correction of the SBT data, gives a dispersion ofmagnitude-luminosity index relation in the VVC system of 0.45 mag, witha slope of 3.0.
| Southern Galaxy Catalogue.
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