Mystery ‘whippet’ space explosion is the brightest of its kind

A mysterious burst of bright light in the sky has puzzled astronomers, with speculation that it could be the result of a black hole consuming a massive, unusually bare star.

In 2018, scientists witnessed a unique cosmic explosion named AT2018cow or “the Cow”, which rapidly reached peak brightness in just a few days, unlike traditional supernovae that take weeks to achieve the same intensity.

This phenomenon, categorized as a fast blue optical transient (FBOT), left scientists scratching their heads due to its unprecedented speed and brightness. Since then, only a few similar events have been observed, leaving the origins of these fast bursts still shrouded in mystery.

Recently, researchers led by Jialian Liu from Tsinghua University in China have proposed a groundbreaking explanation for one of the brightest FBOTs ever recorded, named AT 2024wpp or “the Whippet”. This explosion, detected by the Zwicky Transient Observatory in late 2024, outshone the Cow by a factor of 10.

Through observations using various telescopes, including the Swift X-Ray Telescope and the Australia Telescope Compact Array, Liu and his team discovered that the Whippet emitted light with temperatures six times hotter than the sun’s surface and ejected plasma at speeds approaching one-fifth of the speed of light. Additionally, a month after the initial burst, a secondary surge of X-rays was detected, a phenomenon previously unseen in FBOTs.

Based on their findings, the researchers propose that the Whippet originated from a rare type of star known as a Wolf-Rayet star, characterized by an exposed core devoid of an outer gas layer. They suggest that the event was triggered by the star’s encounter with a black hole 15 times the mass of the sun, resulting in a two-stage explosion.

The initial burst of light was caused by the star’s merger with the black hole, while the subsequent X-ray emission was attributed to the infall of residual material orbiting the black hole. This explanation has garnered support from experts like Ashley Crimes at the European Space Agency, who lauds the hypothesis for its coherence and explanatory power.

Notably, the Whippet’s location in a young galaxy rich in short-lived extreme stars aligns with expectations, further bolstering the credibility of the researchers’ theory. According to Crimes, the evidence of late-time material falling back post-merger adds weight to the argument, painting a promising picture of the cosmic event.