Dwarfs in some close groups of galaxies
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The concentration of dwarf galaxies in a poor group of galaxies can be investigated by comparing the distribution of objects of low surface brightness in the region of the group with its broader neighborhood. Restriction to a single region at a given distance from the group may lead to incorrect conclusions, owing to the very irregular distribution of the faint objects. A study of the neighborhoods of three close groups of galaxies defined by common radial velocities revealed that irregular dwarfs of very low surface brightness (such as NGC 6822, IC 1613 in the local group) exhibit a tendency to concentrate in the same region as giant galaxies. No evidence has been found for the concentration of E-dwarfs with low surface brightness (such as IC 3475) in poor groups of galaxies. The faintest representatives of this type (similar to the systems of Sculptor and Formax) remain beyond the range of visibility on the Palomar charts. Objects which are possible S-dwarfs with very low surface brightness show no tendency to concentrate in the region of poor groups of galaxies.
The author is highly indebted to the Department of Stellar Astronomy of the Shternberg State Astronomical Institute, and especially to Professor B. A. Vorontsov-Vel'yaminov for his help in this research.
KeywordsRadial Velocity Local Group Surface Brightness Single Region Dwarf Galaxy
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