M80 - NGC 6093

Messier 80 (NGC 6093) is a dense globular cluster located approximately 32,600 light-years from Earth in the constellation Scorpius. It was discovered by Charles Messier in 1781 and lies in a rich region of the Milky Way, roughly halfway between the bright stars Antares and Graffias (Beta Scorpii). M80 is one of the most densely concentrated globular clusters in the Milky Way, with a Shapley-Sawyer class of II, meaning its stars are packed extremely tightly toward the center. The cluster spans about 95 light-years in diameter and is believed to have undergone a core collapse, similar to M15 and M70. M80 contains an exceptionally large number of blue straggler stars, far more than expected for a cluster of its size. These blue stragglers are thought to form through stellar collisions and mergers, which are more frequent in the extremely dense core of M80 where stars pass close to one another regularly. In 1860, a nova designated T Scorpii appeared near the center of M80, briefly outshining the entire cluster and reaching 7th magnitude before fading. This was one of only two novae ever observed in a globular cluster (the other was in M14 in 1938). The nova was likely caused by a thermonuclear explosion on the surface of a white dwarf in a close binary system. In amateur telescopes, M80 appears as a small, bright, intensely concentrated ball of light. Its dense core is difficult to resolve even in large amateur instruments, though 8-inch and larger telescopes can begin to pick out individual stars at the periphery. The cluster's bright appearance and compact size give it an almost comet-like quality at low magnification.

M80 spans about 95 light-years in diameter with an extremely dense, likely core-collapsed center, located approximately 32,600 light-years from Earth.