Astronomers have detected a mysterious cosmic explosion known as AT 2024wpp, or the Whippet, which is the brightest fast blue optical transient observed to date. Researchers suggest it resulted from a massive Wolf-Rayet star being devoured by a black hole. The event, spotted at the end of 2024, offers new insights into rare stellar phenomena.
In late 2024, the Zwicky Transient Observatory identified a sudden burst of light in space, designated AT 2024wpp and nicknamed the Whippet. This event rapidly intensified, reaching peak brightness about 10 times greater than that of the Cow, a similar explosion discovered in 2018 and classified as AT2018cow. Both belong to a rare category called fast blue optical transients (FBOTs), which brighten far quicker than typical supernovae and whose origins have puzzled scientists since the Cow's detection.
A team led by Jialian Liu at Tsinghua University in China analyzed the Whippet using multiple telescopes, including the Swift X-Ray Telescope and the Australia Telescope Compact Array. Their observations revealed a light spectrum indicating temperatures over six times hotter than the sun's surface, with plasma ejected at roughly one-fifth the speed of light. Notably, about a month after the initial flash, a secondary burst of X-rays occurred, a feature not previously seen in other FBOTs.
The researchers propose that the Whippet stems from a Wolf-Rayet star—more than 30 times the mass of the sun, stripped of its outer hydrogen layers—merging with a black hole of about 15 solar masses. The initial collision would have produced the first light burst, while orbiting debris later falling back generated the X-ray emission. This scenario aligns with the event's location in a young galaxy, where such extreme, short-lived stars are more prevalent.
Ashley Crimes at the European Space Agency described the explanation as promising, stating, “Of all the different explanations that have been put forward, this one probably has the least problems.” He added, “These are the kinds of environments that you’d expect to see this kind of event, and then, in addition, you see this bump at late times, which could be material falling back after a merger. It’s promising.” The findings are detailed in a preprint on arXiv (DOI: 2602.20523).
