A supernova discovered 6 years ago is actually something much rarer

In a case of cosmic misidentification, six years after its initial discovery, reported in The Astronomer’s Telegram by Carnegie’s Thomas Holoien, researchers, led by Anna Payne of the University of Hawaii at Mānoa, can now say that the phenomenon they observed and they believed a supernova, called ASASSN-14ko, is actually a periodically recurring glow from the center of a galaxy more than 570 million light-years away in the southern constellation of Pictor.

Active galaxies, such as the host of ASASSN-14ko, have unusually bright and variable centers. These objects produce far more energy than the combined contribution of all their stars. Astrophysicists think this is due to gravitational and frictional forces heating a swirling disk of gas and dust that accumulates around the central supermassive black hole. The black hole slowly consumes the material, which creates random low-level changes in the light emitted by the disk.

Credits: NASA / ESA / JHU / R.Sankrit & W. Blair

This is the first unambiguous example of such clockwork behavior from an active galaxy. Periodically recurring flares, such as those of ASASSN-14ko, could be evidence of observational cosmic phenomena that were previously predicted by theorists. ASASSN-14ko was first detected by the All-Sky Automated Survey for Supernovae (ASAS-SN), a global network of 20 robotic telescopes based at Ohio State University (OSU) in Columbus.

Based on this discovery, astronomers predicted that the galaxy would experience another blast on May 17 last year and coordinated ground and space structures to make observations. “ASAS-SN is designed to probe the physics of our universe for transient and variable events,” explained Holoien. “It’s exciting that the bright object that we initially thought was a violent supernova explosion, which would be interesting in its own right, but more common, has turned out to be a long-sought cosmic event.”