Astronomers solve mystery of rare Blue Ring Nebula: two stars merged

Six thousand light-years away, a star that was once two has left behind a glowing ultraviolet ring — a fleeting monument to a collision that happened less than five thousand years ago. Astronomers have at last identified the Blue Ring Nebula, discovered in 2004, as the aftermath of a stellar merger, catching it in the narrow window of cosmic time when it is neither hidden by dust nor yet dissolved into the void. In a galaxy where binary stars are the rule and their collisions are constant yet nearly invisible, this object offers something rare: a clear view of a process that shapes the Milky W