Radio Emission from the Perseus Cluster

Abstract

A RADIO source the position of which coincides closely with the cluster of extragalactic nebulae in the constellation of Perseus has been observed by Ryle, Smith and Elsmore1, by Mills2 and by Hanbury Brown and Hazard3. The last-named authors have suggested that the observed radio emission is to be associated with the cluster as a whole, and they have pointed out that on this hypothesis there is an important discrepancy between the average radio emission of the individual galaxies of the cluster and that of nearby galaxies. Baade and Minkowski4, on the other hand, have suggested that the radio source should be identified with NGC 1275, one of the members of the cluster. This nebula, like that associated with the intense radio source in Cygnus, is probably another example of two galaxies in collision; the optical spectrum contains lines of high excitation and the structure suggests that a collision has taken place between an elliptical and a spiral nebula.