An explosion that was 180 million light years away has been observed by astronomers. This challenges the current knowledge of explosions in space, which appeared much flatter than thought possible.
An explosion that was the size of the solar system has puzzled researchers as part of its shape is identical to that of an extremely flat disc, challenging everything we know about explosions in space.
The explosion noted was a bright Fast Blue Optical Transient (FBOT), which is an extremely unusual class of explosion that is much less common compared to other explosions, like supernovas. The first bright FBOT was founded in 2018 and provided with the nickname “the cow.”
In the universe, explosions of stars are almost constantly spherical, as the stars themselves are spherical.
But this explosion, which occurred nearly 180 million light-years away, is known to be the most aspherical ever seen in space, with a shape like a disc. This section of the explosion might have come from material shed by the star just before the explosion.
Yet, it is to be clearly understood how bright FBOT explosions take place, but it is believed that this observation, reported in the journal Monthly Notices of the Royal Astronomical Society, will take people a step closer to comprehending them.
Dr. Justyn Maund, Lead Author of the study from the University of Sheffield’s Department of Physics and Astronomy, stated, “Very little is known about FBOT explosions-they just don’t behave like exploding stars should, they are too bright and they evolve too quickly. Put simply, they are weird, and this new observation makes them even weirder.”
Maund added, “Hopefully this new finding will help us shed a bit more light on them-we never thought that explosions could be this aspherical. There are a few potential explanations for it: the stars involved may have created a disc just before they died or these could be failed supernovas, where the core of the star collapses to a black hole or neutron star, which then eats the rest of the star.”
What we now know for sure is that the levels of asymmetry recorded are a key part of understanding these mysterious explosions, and it challenges our preconceptions of how stars might explode in the Universe.
Dr. Justyn Maund, Department of Physics and Astronomy, University of Sheffield
This breakthrough was made by the researchers after spotting a flash of polarized light entirely by chance. They were capable of quantifying the polarization of the blast with the astronomical equivalent of polaroid sunglasses and with the Liverpool Telescope (owned by Liverpool John Moores University) situated on La Palma.
By quantifying the polarization, it enabled them to measure the explosion’s shape, which effectively sees something the size of the Solar System but in a galaxy that is 180 million light-years away.
Further, they were able to make use of the data to rebuild the 3D shape of the explosion and were also able to map the edges of the blast—thereby enabling them to see just how flat it was.
The Liverpool Telescope’s mirror is just around 2.0 m in diameter. However, by studying the polarization, the astronomers were capable of reconstructing the shape of the explosion as if the telescope had a diameter of nearly 750 km.
Now, scientists will engage in a new survey with the international Vera Rubin Observatory in Chile, which is anticipated to help find more FBOTs and further gain insights into them.
Maund, J. R., et al. (2023) A flash of polarized optical light points to an aspherical ‘cow’. Monthly Notices of the Royal Astronomical Society. https://doi.org/10.1093/mnras/stad539.