On the Precursors of Fossil Groups

Abstract

We compare the absolute magnitudes in the K-band of the brightest galaxies in clusters of Bautz-Morgan type I with those of the fossil group brightest galaxies. It is found that the brightest galaxies in fossil groups are on average fainter than the brightest galaxies in clusters. It is also shown that the brightness of the brightest galaxy depends on the cluster richness. It is concluded that the precursors of fossil groups were on average poor clusters.