Oops! Earendel, Most Distant Star Ever Discovered, May Not Actually be a Star
upstart writes:
The most distant star ever discovered may have been misclassified: Instead of being a single star, the object - nicknamed Earendel from the Old English word for "morning star" - may be a star cluster, a group of stars that are bound together by gravity and formed from the same cloud of gas and dust, new research suggests.
Discovered by the Hubble Space Telescope in 2022, Earendel was thought to be a star that formed merely 900 million years after the Big Bang, when the universe was only 7% of its current age.
Now, in a study published July 31 in The Astrophysical Journal, astronomers used the James Webb Space Telescope (JWST) to take a fresh look at Earendel. They wanted to explore the possibility that Earendel might not be a single star or a binary system as previously thought, but rather a compact star cluster.
They found that Earendel's spectral features match those of globular clusters - a type of star cluster - found in the local universe.
"What's reassuring about this work is that if Earendel really is a star cluster, it isn't unexpected!" Massimo Pascale, an astronomy doctoral student at the University of California, Berkeley, and lead author of the study, told Live Science in an email. "[This] work finds that Earendel seems fairly consistent with how we expect globular clusters we see in the local universe would have looked in the first billion years of the universe."
Earendel, located in the Sunrise Arc galaxy 12.9 billion light-years from us, was discovered through a phenomenon known as gravitational lensing, a phenomenon predicted by Einstein's theory of general relativity in which massive objects bend the light that passes by them. A massive galaxy cluster located between Earth and Earendel is so large that it distorts the fabric of space-time, creating a magnifying effect that allowed astronomers to observe Earendel's light, which would otherwise be too faint to detect. Studies indicate that the star appears at least 4,000 times larger due to this gravitational lensing effect.
[...] After Earendel's discovery in 2022, researchers analyzed the object using data from JWST's Near Infrared Imager (NIRCam). By examining its brightness and size, they concluded that Earendel could be a massive star more than twice as hot as the sun and roughly a million times more luminous than our star. In the color of Earendel, astronomers also found a hint of the presence of a cooler companion star.
"After some recent work showed that indeed Earendel could (but is not necessarily) be much larger than previously thought, I was convinced it was worthwhile to explore the star cluster scenario," Pascale said..
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