(ORDO NEWS) — The explosion, which took place in a galaxy 180 million light-years away, challenges our understanding of how stars die and appears to be the flattest explosion of its kind on record.
The massive boom, called AT2018cow, belonged to an extremely rare class of cosmic explosions known as fast blue optical transients. or FBOT.
However, unlike the four other FBOTs discovered to date, AT2018cow appears to have only exploded sideways for some reason.
As a result, the eruption is not spherical, as one would expect from the explosion of a spherical object such as a star, but a disk.
Since we don’t know what causes these strangely shaped explosions, this discovery could help astronomers narrow down the list of potential progenitors.
“Very little is known about FBOT explosions – they just don’t behave like stars should explode, they’re too bright and evolve too fast.
Simply put, they are strange, and this new observation makes them even stranger,” says astrophysicist Justin Mound from the University of Sheffield in the UK, who led the study.
“Hopefully this new discovery will help us shed a little more light on them we never thought that explosions could be so aspherical.
There are several possible explanations for this: the stars involved may have created the disk just before they die, otherwise it could be a failed supernova where the star’s core collapses into a black hole or neutron star, which then eats the rest of the star.”
AT2018cow – nicknamed “The Cow” – was the first of these explosions to be discovered back in 2018, and it was immediately identified as highly bizarre.
It was exceptionally bright, so bright that it was originally thought to have happened much closer to us.
In some ways, it was similar to a normal supernova explosion, but astronomers later discovered that it was 10 times more powerful.
The flash erupted and then faded much faster than a normal supernova and was incredibly hot., which gave the light it emitted a much bluer hue than normally seen from normal supernovae.
These traits have been shared with other FBOTs since discovery.
Although explanations for the unusual explosion have been proposed, we are still not entirely sure what causes the FBOT, so astronomers continue to study the data. collected during each event to try and get to the bottom of it.
Mound and his team have done an in-depth study of the Cow’s polarization data from the Liverpool Telescope.
This is the degree of distortion in the orientation of light waves, and it can provide information about the environment in which the light was formed and through which it traveled its long journey to the detectors of our telescopes.
This polarization was extremely high and was recorded at several wavelengths several times during the first night of observations after the explosion, and then in the following days.
This allowed the researchers to reconstruct the three-dimensional shape of the explosion.
Curiously, at the 12-day mark, they observed a “bulge” in the polarization of blue wavelengths, a feature that could be the result of purely aspherical geometry.
It was the polarization profile that led the team to conclude the unusual shape of the Cow presents a mystery.
We have several FBOT detections, which means we are likely to discover more in the future, especially with tools like the powerful Vera C. Rubin Observatory.
Due to start next year, it will scan the skies looking for transient events such as FBOT, among others.
An analysis of the polarization data of these events can show whether a cow is typical of this type of explosion. , or even among eccentrics it was even stranger.
“Now we know for sure that recorded levels of asymmetry are a key part of understanding these mysterious explosions,” says Mound, “and it challenges our preconceptions about how stars might explode in the universe.”
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