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Astronomers Discover Stellar Remnant from Beginning of Universe

Astronomers Discover Stellar Remnant from Beginning of Universe

Tuesday, 26 October, 2021 - 06:30
A black hole located approximately 1,500 light years from our solar system, discovered in the constellation Monoceros, pulls at a nearby red giant star

On Earth, skeletons of animals that lived millions of years ago are known as "fossils," and astronomers decided to use the same name to describe an unusual star that they believe is a stellar remnant of one of the universe's very first stars. Their findings were announced in the latest issue of the journal Astrophysical Journal Letters.

The star, named AS0039, is located in the Sculptor dwarf galaxy around 290,000 light-years from the solar system. This stellar remnant has the lowest concentration of metal, particularly iron, of any star measured outside the Milky Way.

The researchers think that finding is evidence that the remnant is a direct descendent of one of the universe's earliest stars. The team found that the primordial parent star of AS0039 would have been around 20 solar masses and likely died in a hypernova — a stellar explosion 10 to 100 times more powerful than a regular supernova.

"The discovery may reveal new information about the universe's first stars," study co-author Mike Irwin, an astronomer at the University of Cambridge in England, told Live Science.

Stars can be classified into three distinct groups based on their chemical composition, or metallicity. Population I stars, like the sun and most other stars in the observable universe, have high metal content, especially iron. Population II stars, such as AS0039, are much rarer and metal-poor. Population III stars, which have never been seen, are almost totally metal-free and have zero heavy elements.

Although Population III stars have never been detected, astronomers know that the very first stars born in the universe would have been Population III stars, Irwin said.

"When we found AS0039, we were amazed at how metal-poor it was, even compared with other Population II stars. It has the lowest metal concentration of any star studied outside our own galaxy," he added.

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