Thursday, May 19, 2022

Astronomers puzzled by cow in the sky

A huge space explosion and don’t know what it is.

In space, stars go supernova in brilliant bursts of light. Now, astronomers have detected a mysterious cataclysm in a neighboring galaxy. This puzzled astronomers around the world scrambling to understand the source of the staggeringly brilliant flash.

On 17 June, the twin ATLAS telescopes in Hawaii spotted a bright flash in space that hadn’t been there when they’d checked about two days before. According to astronomers, this immense flash coming to us from another galaxy, 200 million light-years away and, this flash must have been 10 to 100 times brighter than a typical supernova.

Initially, astronomers thought that it originated in our own galaxy. They thought it might be what’s called a cataclysmic variable star, typically two stars orbiting one another and interacting in a way that increases the whole system’s brightness irregularly. But subsequent spectroscopic observations showed the explosion came from another galaxy – labeled CGCG 137-068 – located some 200 million light-years away in the direction of the constellation Hercules.

Named AT2018cow, the transient was soon given the nickname ‘cow’. This is not due to any resemblance to the quadruped but a mere coincidence of letters in the way of naming such transients.

Stephen Smartt, an astrophysicist at Queen’s University Belfast and a lead scientist for the Hawaii-based ATLAS survey, which first observed the object said, “I’ve never seen anything like this before in the local universe.”

As to what caused this intense blast, scientists don’t know yet, but they say that it is composed of a 16,000 degree Fahrenheit (9,000 degree Celsius) cloud of high-energy particles, expanding outward at 12,000 miles (20,000 kilometers) per second. It is also very bright in all parts of the electromagnetic spectrum, and its spectrum is also “surprisingly smooth,” unlike most supernovae which have distinct absorption lines.

After the flash was reported, astronomers used at least 18 telescopes from around the world to study the occurrence.

Robert Rutledge, editor-in-chief of The Astronomer’s Telegram and an astrophysicist at McGill University in Canada said, “I think it’s the most notices for any individual object in such a short period of time. It has produced a lot of interest.”

As astronomer Kate Maguire of Queen’s University Belfast noted, “There are other objects that have been discovered that are as fast, but the fastness and the brightness, that’s quite unusual. There hasn’t really been another object like this.”

“We’re not sure yet what it is, but the normal powering mechanism for a supernova is a radioactive decay of nickel, and this event is too bright and too fast for that.”

The astronomers reported the explosion on June 17, 2018, in The Astronomer’s Telegram.


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