Located some 75 million light-years away in the constellation of Aquarius, the Kinman Dwarf galaxy is too far away for astronomers to see its individual stars. But they can detect some of them. The light from the galaxy consistently showed evidence that it hosted a 'luminous blue variable' star some 2.5 million times brighter than the Sun. But the star was absent from the data the team collected in 2019, leaving them to wonder what had happened to it.
Stars of this type are unstable, showing occasional dramatic shifts in their spectra and brightness. Between 2001 and 2011, various teams of astronomers studied the mysterious massive star. But in August 2019 when they pointed European Southern Observatory's Very Large Telescope (VLT) to the distant galaxy, they could no longer find the signatures of the star. A few months later, a group of scientists tried the X-shooter instrument, also on ESO's VLT, and again found no traces of the star.
Based on their observations and models, the astronomers have suggested two explanations for the star's disappearance and lack of a supernova, related to this possible outburst. The outburst may have resulted in the luminous blue variable being transformed into a less luminous star, which could also be partly hidden by dust. Alternatively, the team says the star may have collapsed into a black hole, without producing a supernova explosion.