M15 - GREAT PEGASUS CLUSTER

Messier 15, the Great Pegasus Cluster, is one of the most densely concentrated globular clusters known, located approximately 33,600 light-years from Earth in the constellation Pegasus. It contains an estimated 100,000 or more stars within a diameter of about 175 light-years and shines at an apparent magnitude of 6.2, making it visible in binoculars and detectable with the naked eye under ideal conditions. M15 was discovered by the Italian astronomer Jean-Dominique Maraldi in 1746 while searching for a comet, and Charles Messier cataloged it in 1764. The cluster is classified as Class IV on the concentration scale, indicating an extremely dense core. In fact, M15 is one of the densest known globular clusters and has undergone what astronomers call "core collapse," a process where gravitational interactions between stars cause the core to contract to an extraordinarily high density. This has led to speculation that M15 may harbor an intermediate-mass black hole at its center, with estimates ranging from a few hundred to a few thousand solar masses, though this remains debated. M15 is also notable for containing Pease 1, one of only four planetary nebulae known to exist within a globular cluster, which was discovered in 1928. The cluster is home to over 100 known variable stars and at least 8 pulsars detected by radio telescopes. With an estimated age of about 12.3 billion years, M15 is one of the oldest globular clusters in the Milky Way. Through a telescope, it presents a brilliant, intensely bright core that fades into a beautiful halo of resolved stars.

Contains over 100,000 stars within 175 light-years diameter, located 33,600 light-years away, with one of the densest known cores of any globular cluster.