By Elton Gomes
A team of astronomers from the Johns Hopkins University have detected what they believe could be one of the universe’s oldest stars, made almost entirely of materials formed by the Big Bang.
The newly found star is believe to reside in the same part of the Milky Way galaxy as our own solar system, and it is estimated to be up to 13.5 billion years old. The star’s age is evidenced by its extremely low metal content, or metallicity, Xinhua news agency reported.
The star is unusual because unlike other stars with very low metal content, it has been found in the Milky Way’s “thin disk”—the part of the galaxy wherein our own sun resides. And because the newly found star is so old, researchers now believe that our galactic neighborhood could be at least 3 billion years older than previously thought.
Researchers were able to figure out that the star is so old due to its metal composition. As stars die and their leftover materials form new stars, the nuclear fusion reactions that power their cores exude heavy metals like gold and platinum. A large amount of heavy metals indicate that a star must have been through more generations.
What has the study found?
According to the study’s co-author Andrew Casey, it was previously believed that the first stars, which were formed in the universe, could not be in existence till date.
“The findings are significant because for the first time we have been able to show direct evidence that very ancient, low mass stars do exist, and could survive until the present day without destroying themselves,” Casey said, IANS reported.
Stars that were formed at the beginning of the universe are believed to have consisted entirely of elements like hydrogen, helium, and small amounts of lithium. This could indicate why the newly found star has extremely low metal content. The researchers thus noted that the star could be as little as one generation removed from the beginning of the universe.
The newly discovered star could be a record holder for the star with the smallest complement of heavy elements. Astronomers also found around 30 ancient “ultra metal-poor” stars with the approximate mass of the sun. The new star, however, is only 14 percent the mass of the sun.
“This star is maybe one in 10 million,” said lead author Kevin Schlaufman, an assistant professor of physics and astronomy at Johns Hopkins University. “It tells us something very important about the first generations of stars,” Phys.org reported.
Why is this important?
The star is part of a two-star system orbiting around a common point. Schlaufman and his team detected the tiny, almost invisibly faint “secondary” star after another group of astronomers found the much brighter “primary” star.
That team measured the primary star’s composition by studying a high-resolution optical spectrum of its light. Here, the team found that the star had extremely low metallicity. Those astronomers also identified unusual behavior in the primary star’s system, which implied the presence of a neutron star or a black hole.
However, Schlaufman and his team found the inference to be incorrect, but in doing so, they discovered the visible star’s much smaller companion.
The existence of the smaller companion star turned out to be the big discovery. The discovery of this new ultra metal-poor star, named 2MASS J18082002-5104378 B, paves the way for observing even older stars.
“If our inference is correct, then low-mass stars that have a composition exclusively the outcome of the Big Bang can exist,” said Schlaufman, Science Daily reported. “Even though we have not yet found an object like that in our galaxy, it can exist.”
Elton Gomes is a staff writer at Qrius