Einstein Observations of the Virgo Cluster

The Virgo cluster is discussed with reference to observations of individual galaxies made by the Einstein X-ray Observatory. The X-ray image of M87 as seen by the image proportional counter is presented, noting that its optical galaxy is fairly small and that most of its X-ray emission is beyond the optically bright portion of the galaxy. The emission is highly symmetrical and there is no evidence for differences from a purely radial distribution. Values are given for the surface brightness distribution of M87 components: the visible galaxy, the gas, and the dark halo. The X-ray image of the field containing M86 and M84 is presented, and five X-ray sources are visible. The galaxies in this field are discussed. The extended X-ray emission surrounding M86 suggests that the core radius for the density distribution is about 3 arcmin. The emission spectrum is similar to that of M87, though apparently somewhat cooler. M86 is further described in terms of its evolution in a hot cluster gas environment, and its very high velocity of approach.