Globular Cluster M 15

Pegasus Cluster

Globular cluster M15 in the constellation Pegasus. It is located approximately 33,600 light-years from Earth. M15 is one of the densest globular clusters in our Galaxy. It contains over 100,000 stars.
The core of this cluster has undergone compression (a phenomenon known as "core collapse") and features a central density peak, surrounded by a vast number of stars and possibly containing a black hole.

M15 contains a relatively large number of variable stars, 112 of which are located in its core. At least nine pulsars have been found in the cluster, including one possible double pulsar system. M15 also contains the planetary nebula Pease 1, discovered in 1928, which is one of only four planetary nebulae known to exist within globular clusters.