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Designated WHL0137-LS and nicknamed Earendel, the newly-detected star emitted its light around 900 million years after the Big Bang.
Earendel (arrow) is positioned along a ripple in spacetime that gives it extreme magnification, allowing it to emerge into view from its host galaxy, which appears as a red smear across the sky. The whole scene is viewed through the distorted lens created by the galaxy cluster WHL0137-08 in the intervening space, which allows the galaxy’s features to be seen, but also warps their appearance — an effect astronomers call gravitational lensing. The red dots on either side of Earendel are one star cluster that is mirrored on either side of the ripple, a result of the gravitational lensing distortion. The entire galaxy, called the Sunrise Arc, appears three times, and knots along its length are more mirrored star clusters. Earendel’s unique position right along the line of most extreme magnification allows it to be detected, even though it is not a cluster. Image credit: NASA / ESA / B. Welch, JHU / D. Coe, STScI / A. Pagan, STScI.
Earendel is so far away that its light has taken 12.9 billion years to reach Earth, appearing to us as it did when the Universe was only 7% of its current age, at redshift 6.2.
The smallest objects previously seen at such a great distance are clusters of stars, embedded inside early galaxies.
“We almost didn’t believe it at first, it was so much farther than Icarus, the previous most-distant, highest redshift star,” said Dr. Brian Welch, an astronomer at the Johns Hopkins University.
Earendel was discovered by Hubble’s Reionization Lensing Cluster Survey (RELICS) program.
“When the light that we see from Earendel was emitted, the Universe was less than a billion years old, only 6% of its current age,” added Dr. Victoria Strait, a postdoctoral researcher at the Cosmic Dawn Center, the Niels Bohr Institute at the University of Copenhagen, and the University of California, Davis.
“At that time it was 4 billion light-years away from the proto-Milky Way, but during the almost 13 billion years it took the light to reach us, the Universe has expanded so that it is now a staggering 28 billion light-years away.”
“The previous record is a star seen when the Universe was around a third of its current age, at which time most of its structure had already formed and evolved. So Earendel is indeed a ground-breaking record.”
The astronomers estimate that Earendel is at least 50 times the mass of our Sun and millions of times as bright, rivaling the most massive stars known.
But even such a brilliant, very high-mass star would be impossible to see at such a great distance without the aid of natural magnification by a massive galaxy cluster, WHL0137-08, sitting between us and Earendel.
WHL0137-08’s mass warps the fabric of space, creating a powerful natural magnifying glass that distorts and greatly amplifies the light from distant objects behind it.
Thanks to the rare alignment with the magnifying galaxy cluster, Earendel appears directly on, or extremely close to, a ripple in the fabric of space. This ripple, which is defined in optics as a caustic, provides maximum magnification and brightening.
“Normally at these distances, entire galaxies look like small smudges, with the light from millions of stars blending together,” Dr. Welch said.
“The galaxy hosting this star has been magnified and distorted by gravitational lensing into a long crescent that we named the Sunrise Arc.”
“Earendel existed so long ago that it may not have had all the same raw materials as the stars around us today.”
“Studying this star will be a window into an era of the universe that we are unfamiliar with, but that led to everything we do know. It’s like we’ve been reading a really interesting book, but we started with the second chapter, and now we will have a chance to see how it all got started.”
The discovery is described in a paper published in the journal Nature.
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B. Welch et al. 2022. A highly magnified star at redshift 6.2. Nature 603, 815-818; doi: 10.1038/s41586-022-04449-y
Source link: https://www.sci.news/astronomy/earendel-10669.html
Source link: https://vietnet.org/hubble-uncovers-most-distant-star-ever-seen/
