Sunday , April 11 2021

Astronomers have encountered one of the oldest stars in the universe

The place of the newly discovered ancient star.
Image: ESO / Beletsky / DSS1 + DSS2 + 2MASS

A small star that was about 1,590 light years from Earth could be 13,53 billion years old, making it one of the oldest stars ever discovered.

The "ultra metal" mini-star is called 2MASS J18082002-5104378 B, later abbreviated to J1808-5104, and was revealed by a team of astronomers led by Kevin C. Schlaufman of Johns Hopkins University. About 13.53 billion years of age, among the first generations of stars emerged after the Great Bore, which occurred 13.7 billion years ago. Not only is it one of the oldest stars on the Milky Way but one of the oldest stars in the universe. Details of this finding will be published in the upcoming issue of Astrophysical Magazine, but pre-print is published in arxiv.

"This star is perhaps one in 10 million," Schlaufman said in a statement. "It tells us something very important for the first generation of stars."

Indeed, the discovery provokes prejudices about what were the earliest stars and where they were.

The first generation of stars that appear after the Big Bang consist exclusively of elements such as hydrogen, helium and lithium trace amounts. When these primordial stars exploded as supernovaes, they exaggerated the cosmos with the heavy elements that were built into the next generation of stars. Thus, metal content or metallic stars increased because the cycle of death and birth continued throughout the Eona.

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To date, astronomers have discovered about 30 star stars, the metal poor, tending to be as massive as ours. But J1808-5104 is only 14 percent of our Sun's mass, leading Schlaufman and his colleagues to speculate that it is a red dwarf.

The newly discovered star, which astronomers have analyzed using Magellan's clay telescope, the Las Campanas observatory and the Gemini Observatory, are exceptionally metallic. And, in fact, it has the smallest amount of heavy elements ever recorded in the stars, which have roughly the same content of heavy elements as the planet Mercury. The amount of heavy items in the J1808-5104 is so low, researchers say it could only be one generation removed from the Big Bang. Before the new discovery, Caffau's star was considered the most unusual star of a star – a star that is only slightly smaller than our Sun.

The new star is only 14 percent of the mass of the Sun, which contains the smallest addition to the heavy elements of any known star.
Photo: Kevin Schlaufman / JHU

The stars of the size of our Sun are about 10 billion years old, but small mass stars like this could be theoretically burning for a thousand years.

"Minor stars like these tend to shine very long," Schlaufman said. "This star has gone well, it looks exactly the same as it was when it was 13.5 billion years ago."

The place of the star on the Milky Way is also strange; J1808-5104 is part of the "thin disc" of the galaxy, where the Sun is. There should not be old stars of the metal poor, active, full of areas with many younger stars. The finding shows that the thin disk of the Milky Way is about 3 billion years older than it used to be.

J1808-5104 is a smaller member of the two-star system. Measuring the "twisting" of a bigger star, caused by the gravitational influence of a smaller star, astronomers could carry the mass of J1808-5104. High resolution optical spectroscopy was used to identify elements such as carbon, oxygen, iron and others.

The new discovery is fascinating, but it is strange and unexpected, so other scientists should repeat other astronomers to make sure that Schlaufman and his team are not mistaken. That discovery, the discovery J1808-5104 points to the older stars on the Milky Way. As an even older star is revealed, let's find out more about the universe during its earliest times.

[The Astrophysical Journal]

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