NASA/ESA’s Hubble Telescope has recently photographed the globular cluster Messier 15 in unprecedented detail by combining the observations of the Wide Field Camera 3 and the Advanced Camera for Surveys within the infrared, optical and ultraviolet parts of the electromagnetic spectrum.
Messier 15 is one of the oldest globular clusters in the universe situated 35,000 light years away from us, within the Pegasus constellation. A globular cluster is a more or less spherical cluster of stars that orbit a central point within the galaxy. Within the cluster, hot blue stars and cooler orange/yellow stars exist side by side, becoming more concentrated towards the centre of the cluster giving the cluster a bauble like appearance.
Observations of this cluster in 2002 revealed a dark and mysterious centre which is either comprised of an intermediate mass black hole or a dark neutron star. The black hole is believed to be the most probable option and could have formed in one of three ways: either during the Big Bang, the amalgamation of several smaller mass black holes or the collision of two massive stars. The observations of the heart of this cluster could therefore provide insight into the growth and evolution of black holes.
Read more at: http://www.spacetelescope.org/news/heic1321/