28/12/2025
First-ever 'superkilonova' double star explosion puzzles astronomers
A double explosion, in which a dying star split, then recombined, may be a long-hypothesized but never-before-seen "superkilonova." Scientists may have witnessed a massive, dying star split in two and then crash back together, triggering a never-before-seen double explosion. The explosion sent ripples through space-time and forged some of the universe's heaviest elements. Most massive stars reach the ends of their lives by collapsing and exploding as supernovas, seeding the cosmos with elements such as carbon and iron. A different kind of cataclysm, known as a kilonova, occurs when the ultradense remnants of dead stars, called neutron stars, collide, forging even heavier elements like gold.
The newly identified event, named AT2025ulz, appears to combine these two types of cosmic explosions in a way that scientists have long hypothesized but never before observed. If confirmed, it could represent the first example of a "superkilonova," a rare hybrid blast in which a single object produces two distinct but equally dramatic explosions. AT2025ulz first caught astronomers' attention on Aug. 18, 2025, when gravitational wave detectors operated by the U.S.-based Laser Interferometer Gravitational-Wave Observatory (LIGO) and its European partner, Virgo, registered a subtle signal consistent with the merger of two compact objects.
