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IC3328: A ``dwarf elliptical galaxy'' with spiral structure
We present the 2-D photometric decomposition of the Virgo galaxyIC3328. The analysis of the global light distributionof this morphologically classified nucleated dwarf elliptical galaxy(dE1,N) reveals a tightly wound, bi-symmetric spiral structure with adiameter of 4.5 kpc, precisely centered on the nucleus of the dwarf. Theamplitude of the spiral is only three percent of the dwarf's surfacebrightness making it the faintest and smallest spiral ever found in agalaxy. In terms of pitch angle and arm winding the spiral is similar tothe intermediate-type galaxy M51, but it lacks the dust and prominent HIi regions which signal the presence of gas. The visual evidence of aspiral pattern in an early-type dwarf galaxy reopens the question onwhether these dwarfs are genuine rotationally supported or anisotropicstellar systems. In the case of IC3328, we argue for a nearly face-ondisk (dS0) galaxy with an estimated maximum rotation velocity ofvc,max~ 55 km s-1 . The faintness of the spiraland the small motions within it, suggests that we could be seeingswing-amplified noise. The other possibility is a tidal origin, causedby the near passage of a small companion. Based on observationscollected at the European Southern Observatory (ESO 63.O-0055)
| Studies of the Virgo Cluster. II - A catalog of 2096 galaxies in the Virgo Cluster area.
The present catalog of 2096 galaxies within an area of about 140 sq degapproximately centered on the Virgo cluster should be an essentiallycomplete listing of all certain and possible cluster members,independent of morphological type. Cluster membership is essentiallydecided by galaxy morphology; for giants and the rare class of highsurface brightness dwarfs, membership rests on velocity data. While 1277of the catalog entries are considered members of the Virgo cluster, 574are possible members and 245 appear to be background Zwicky galaxies.Major-to-minor axis ratios are given for all galaxies brighter than B(T)= 18, as well as for many fainter ones.
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