A stellar collision is the coming together of two stars caused by stellar dynamics within a star cluster, or by the orbital decay of a binary star due to stellar mass loss or gravitational radiation, or by other mechanisms not yet well understood.
Astronomers predict that events of this type occur in the globular clusters of our galaxy about once every 10,000 years. On 2 September 2008 scientists first observed a stellar merger in Scorpius (named V1309 Scorpii), though it was not known to be the result of a stellar merger at the time.Any stars in the universe can collide, whether they are 'alive', meaning fusion is still active in the star, or 'dead', with fusion no longer taking place. White dwarf stars, neutron stars, black holes, main sequence stars, giant stars, and supergiants are very different in type, mass, temperature, and radius, and so react differently.A gravitational wave event that occurred on 25 August 2017, GW170817, was reported on 16 October 2017 to be associated with the merger of two neutron stars in a distant galaxy, the first such merger to be observed via gravitational radiation.