Center of M15
Messier 15 is one of the most highly compressed globulars in the sky. Astronomers using the Hubble Space Telescope found evidence that it has a black hole in the center. An unusual feature of M15 is Pease 1
, the remains of an exploded star called a ''planetary nebula''. Only thee other globular clusters are known to contain a nebula like this one.
Credit: The Hubble Heritage Team (AURA/STScI/NASA)