A Stellar Swarm in Pegasus

M15
By Barry Chase

Perhaps the most dense of the Milky Way’s globular clusters, M15 lies about 33,600 light years away and is about 175 light years in diameter. It has undergone a core collapse and half the mass of the cluster resides within a 10 light year radius of its center. It is not clear whether this dense concentration is due to the gravitational interactions of the clusters stars, or if it is due to the influence of a supermassive object–a black hole–at its core. M15 is also the first globular cluster in which a planetary nebula was found. (This planetary nebula, Pease 1, is a considered a challenging target for amateur astronomers with large telescopes, dark steady skies, and lots of patience.)

Source: SEDS