Slim Boom. Credit: Phil Drury, University of Sheffield
Astronomers have observed an explosion 180 million light years away that contradicts our current understanding of the cosmic explosion, and reveals a much flatter appearance than previously thought.
- Astronomers observed the explosion 180 million light years away, challenging our current understanding of the explosion in outer space, which appears much flatter than previously thought.
- Explosions are always expected to be spherical, as stars themselves are spherical, but this is the flattest of all
- The observed explosions are extremely rare fast blue light bursts (FBOT) – colloquially known among astronomers as “cows” – only four others have ever been seen, and scientists have no idea how they happened, but this discovery helps solve some of the of puzzles.
- A possible explanation for how this explosion occurred is that the star itself may have been surrounded by a dense disk or it may have been a failed supernova.
An explosion the size of our solar system has scientists baffled, because its shape – similar to a very flat disc – challenges everything we know about explosions in outer space.
The explosion observed was a fast blue bright burst of light (FBOT) – an extremely rare class of explosion that is much less common than other explosions, such as supernovas. The first bright FBOT was discovered in 2018 and nicknamed Cow.
The starbursts in the universe are almost always spherical, because the stars themselves are spherical. However, this explosion, which occurred 180 million light years away, is the most spherical ever seen in space, with a disc-like shape appearing just days after its discovery. This part of the explosion may have been caused by material ejected by the star just before it exploded.
It’s still not clear how bright the FBOT outburst was, but it’s expected from this observation, which was recently published in the journal Monthly Notices of the Royal Astronomical SocietyThat will bring us closer to understanding it.
Dr Justin Maund, lead author of the study from the University of Sheffield’s Department of Physics and Astronomy, said: “Very little is known about FBOT bursts – they don’t behave like supernovae, are very bright and evolve very quickly. Simply put, they are weird, and these new observations make them even weirder.”
“We hope this new discovery will help us explain more about them – we never thought explosions weren’t spherical. There are several possible explanations for this: perhaps the stars in question created a disk just before their death or this could be a failed supernova, in which the star’s core collapses into a black hole or neutron star, which then devours the rest of the star.
“What we now know for sure is that the degree of asymmetry recorded is critical to understanding these mysterious explosions, and challenges our previous assumptions about how stars explode in the universe.”
Scientists made the discovery after spotting an accidental flash of fully polarized light. They were able to measure the polarization of the burst – using Polaroid-equivalent astronomical glasses – with the Liverpool Telescope (owned by Liverpool John Moores University) located in La Palma.
By measuring polarimetry, it allowed them to measure the shape of the explosion, effectively seeing something the size of our solar system but in a galaxy 180 million light years away. Then they can use that data to reconstruct the 3D shape of the explosion, and can map the edges of the blast – allowing them to see how flat the blast is.
The Liverpool Telescope’s mirror diameter is only 2.0 meters, but by studying its polarization, astronomers have been able to reconstruct the shape of the explosion as if it were a telescope with a diameter of about 750 kilometers.
The researchers will now conduct a new survey with the Vera Rubin International Observatory in Chile, which they hope will help find more FBOTs and better understand them.
References: “Optical polarized light flicker refers to a nearly spherical ‘cow’” by Justin R. Mond, Peter A. Hoeflich, Ian A. Steele, Wei Yang, Klas Wiersima, Shiho Kobayashi, Nuria Jordana-Metjans, Carol Mondale, Andrea Gombuck, Cristiano Gidorzi and Robert J. Smith, 21 Feb. 2023, Available here. Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stad539
