Astronomers were astounded to discover a strange explosion in a galaxy 200 million light-years away in 2018. It was unlike any other supernova astronomers seen because it was both shorter and brighter. The event was given the official name AT2018cow, but it quickly gained a more lighthearted moniker: the Cow.

The transient - a short-lived event - defies explanation. Some speculated that it could be a star being ripped apart by a nearby black hole. In contrast, others suggested a "failed supernova" scenario, in which a black hole eats a star from the inside out. They needed to find more Cow-like instances to be certain. They obtained one after more than two years.

NASA's WISE Telescope Reveals Millions Of Black Holes
(Photo: NASA/ESAvia Getty Images)
IN SPACE: In this handout from NASA/ESA, an artist's concept illustrates a quasar or feeding black hole. NASA's Wide-field Infrared Survey Explorer (WISE) revealed millions of potential black holes in its survey of the sky in 2011.

Why is This Cow Misbehaving?

On October 12, 2020, telescopes throughout the world watched as something 3 billion light-years away got tremendously bright, then vanished from view. Astronomers noted in an article titled "Real-Time Discovery of AT2020xnd: A Fast, Luminous Ultraviolet Transient With Minimal Radioactive Ejecta," which behaved almost identically to the Cow, leading them to believe that it must be the same type of incident. It was given its own animal-inspired name, the Camel, in keeping with tradition.

The Cow emerged out of nowhere, and astronomers had no idea what they were looking at when it did. The Camel, on the other hand, was like a thief who had tripped the new alarm system.

Four days later, the scientists utilized telescopes in the Canary Islands and Hawaii to gather crucial information about its features. They later used a service called the Astronomer's Telegram to send out an alarm to other astronomers.

There were two names given to the event. The first, AT2020xnd, comes from a global inventory of all transients, while the second, ZTF20acigmel, was discovered at the Zwicky Transient Facility. The latter became the team's nickname, "Camel."

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The Camel, like its predecessor, became extremely brilliant in a short period of time, peaking in two or three days. It evolved around 100 times brighter than any other form of a supernova. Then it faded away quickly, in a matter of days rather than weeks.

Is This Cow A Black Hole? Maybe, Experts Say

Scientists believe, per Science Magazine, that intense matter jets ejected from the neutron star or black hole shattered the outer shells of material, causing the object to seem very bright.

A preprint on the Research Square portal, titled "Evidence for a Compact Object in the Aftermath of the Extra-Galactic Transient AT2018cow," said scientists have discovered such a thing inside the Cow.

The scientists examined x-ray radiation released by the Cow for 60 days after the explosion using the Neutron Star Interior Composition Explorer telescope on the International Space Station. They concluded that the item producing the light was spinning once every 4.4 milliseconds after accurately measuring the arrival of the photons.

Experts believe a black hole explanation is more feasible than a neutron star explanation since the rotation speed remained constant at 4.4 milliseconds even after billions of observed spins. A neutron star's rotation speed would be expected to diminish over time.

The Cow has been dubbed a "Rosetta Stone event" that could interpret additionally failed supernovae. Since experts noted an event they hope they could understand, they believe this phenomenon could help them know how black holes are formed.

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