Distribution of Dwarf Galaxies in the Virgo and Fornax Clusters.

61, 69, 1956; Publ. Astron. Soc. Pac~fic 74, 392,1962) show their areal distribution (projected on the plane of the sky) to be strikingly similar to that of the normally bright galaxies in the cluster. By contrast, inspection of Hodge's plot (Publ. Astron. Soc. Pac~fic 72,188, Fig. 1,1960) showing the distribution of 12 dwarf ellipticals in the Fornax cluster suggests that in it the degree of association is not nearly so close as in Virgo. Some results from a new survey of Fornax based on Palomar Observatory 48-in. Schmidt plates are reported here. Fifty-one early- type dwarfs were found over an area including the Fornax cluster and its surroundings; the areal distribution of these dwarfs is much less closely associated with that of the normally bright galaxies than is the case in Virgo. The closeness of the association of dwarfs with normally bright galaxies may be quantitatively expressed by the median of the projected distances from each dwarf galaxy to the nearest normally bright cluster member r. This is compared with the median of the projected distances from each normal galaxy to the nearest normal galaxy R. The ratio R/r is a measure of the closeness of the association of dwarf with normal that is independent of the density of the cluster. r R R/r Virgo l3Okpc l3Okpc 1.0 Fornax 140 80 0.6 Since for both clusters, r ~ R, the hypothesis that these dwarfs are satellites of individual galaxies is untenable. These data may also be cited as evidence indicating that the evolutionary age of the Fornax cluster is greater than that of the Virgo cluster.