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'A whole new insight about stars in the early universe'

US, Israeli scientists document oldest star ever seen, 13 billion light-years away

Light detected is so old it’s from when the universe was just 7% of its current age; Israeli professor plays key role in verifying the finding

Nathan Jeffay is The Times of Israel's health and science correspondent

A highly magnified image of the star Earendel. The collection of yellow-looking galaxies form the massive galaxy-cluster lens that magnifies background objects lying behind it. The inset shows the highly magnified red galaxy, host to Earendel, stretched into an arc due to lensing, and the highly magnified star is marked with a white arrow. (NASA, ESA, Brian Welch, Dan Coe)
A highly magnified image of the star Earendel. The collection of yellow-looking galaxies form the massive galaxy-cluster lens that magnifies background objects lying behind it. The inset shows the highly magnified red galaxy, host to Earendel, stretched into an arc due to lensing, and the highly magnified star is marked with a white arrow. (NASA, ESA, Brian Welch, Dan Coe)

American and Israeli scientists have captured and documented images from the Hubble space telescope showing the most distant star ever seen, in a finding they say “opens a door to learn about stars in the early universe.”

The light they saw from the star — newly named Earendel — had traveled 12.9 billion years to reach Earth, appearing as it did when the universe was just 7 percent of its current age. Given that the previous record was 9 billion years, they say it is a major leap.

Prof. Adi Zitrin of Ben-Gurion University in Beersheba was part of the US-led study, newly peer-reviewed and published in Nature.

He told The Times of Israel that he was “excited and amazed” by the finding, and said it succeeded because the stars were, quite literally, aligned.

Detection systems on Earth aren’t generally powerful enough to see such light, but a large galaxy cluster called WHL0138-08 has such a large gravitational pull that light bends around it, and ends up being magnified by a factor of thousands.

Zitrin is one of the top experts on this kind of magnification, and is part of an international research group that hunts for galaxies and stars that are visible as a result of it. So when the lead author, Brian Welch of Johns Hopkins University, thought he had seen an ancient star, Zitrin’s skills were called in to verify it.

The Hubble telescope as seen from the shuttle Discovery, February 1997. (NASA/Public Domain)

“I built a model that mimics the way that the galaxy cluster between Earendel and Earth acted as a ‘gravitational magnifying lens,’” Zitrin said. “This model, subsequently tweaked by Brian, was used to assess whether the light we were seeing looked as light from a very old star would appear.”

When Welch emailed to say his model indicated that it was, indeed, 12.9 billion-year-old light from a star, “I was very excited,” he said.

Prof. Adi Zitrin (Courtesy Ben-Gurion University)

Zitrin explained: “This model was important to eliminate the possibility we were seeing objects along the way, a cluster of stars but not a single star — which would have still been an important finding but less exciting. My model was one of a handful used to verify the finding.”

He added: “The international team I’m part of, which images galaxy clusters that act as ‘gravitational magnifying lenses,’ initially expected to find just galaxies, not individual stars. But happily, we found one in 2018, and this one now.

“Newly discovering this star opens a door to learn about stars in the early universe, as we have hardly any information on stars from so long ago. This finding has given a whole new insight, which will lead to far more research.”

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