A distant galaxy has been erupting in brilliant flares like cosmic clockwork since 2014, revealing the tortured demise of a star ensnared by a supermassive black hole, as confirmed by expert astronomers.
It began in November 2014 when the All Sky Automated Survey for SuperNovae (ASAS-SN), an automated supernova detection program led by Ohio State University astronomers, detected a bright flash from a galaxy 570 million light-years away. Initially classified as a typical supernova—the explosive death of a star—the event puzzled researchers.
Years later, a team reanalyzing ASAS-SN data identified seventeen additional similar flares from the same location, each occurring precisely 114 days apart. This ruled out a one-off supernova, pointing instead to a star in a lethal, highly elliptical orbit around a supermassive black hole.
Supermassive black holes unleash immense energy when they tear apart nearby stars through tidal disruption, emitting powerful electromagnetic radiation and sometimes relativistic jets. These tidal disruption events (TDEs) are typically singular occurrences.
In this case, the star's elongated orbit brings it perilously close to the black hole every 114 days, partially shredding it and triggering repeatable flares—unlike the circular paths of stable orbits like Earth's around the Sun.
To confirm the periodicity, researchers predicted flares for 2020 on May 17, September 7, and December 26—all observed exactly as forecast. "It's really exciting. We've seen black holes do a lot of things, but we've never seen them erupt so regularly," says Patrick Vallely, co-author of the study.
This discovery, poised for publication in The Astrophysical Journal, equips astronomers to hunt for similar repeating TDEs, deepening our understanding of black hole accretion processes drawn from decades of observational expertise.
