Science Daily shares news from NASA/Goddard that Hubble, the space telescope supposedly surpassed by the new Webb telescope, has now identified the farthest star (and thus longest-ago light) ever seen:
Scientists use the word “redshift” because as the universe expands, light from distant objects is stretched or “shifted” to longer, redder wavelengths as it travels toward us.
The newly detected star 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 percent 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 the previous most-distant, highest redshift star,” said astronomer Brian Welch of the Johns Hopkins University in Baltimore, lead author of the paper describing the discovery, which is published in the March 30 journal Nature.
After studying the galaxy in detail, Welch determined that one feature is an extremely magnified star that he called Earendel, which means “morning star” in Old English. The discovery holds promise for opening up an uncharted era of very early star formation.
“Earendel existed so long ago that it may not have had all the same raw materials as the stars around us today,” Welch explained. “Studying Earendel 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,” Welch said.
The research team estimates 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 huge galaxy cluster, WHL0137-08, sitting between us and Earendel. The mass of the galaxy cluster 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, the star 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.
Astronomers expect that Earendel will remain highly magnified for years to come. It will be observed by NASA’s James Webb Space Telescope. Webb’s high sensitivity to infrared light is needed to learn more about Earendel, because its light is stretched (redshifted) to longer infrared wavelengths due to the universe’s expansion.
You can read more of Welch’s research here, in Nature.