The distant stellar system gets its official name WHL0137-LS, but astronomers who found it named it “Earendel” from the Old English word meaning “morning star” or “rising light”. The Earendel system as we see it today glowed just 900 million years after the Big Bang, according to the authors of a new paper in the journal Nature describing the discovery. It took a total of 12.8 billion years before this light reached the Hubble Space Telescope, magnified by a lucky trick of gravity to appear as a tiny photon blur on the Hubble image sensor. Earendel is 8.2 billion years older than the Sun and Earth and 12.1 billion years older than the first animals on our planet. Even by the standards of the ancient stars, Earendel stands out: astronomers have observed the previous record holder, nicknamed Icarus, as he appeared 9.4 billion years ago – 3.4 billion years later than this new record holder. . Even the oldest known supernovae, usually the brightest and most easily detected individual objects in all the vastness of space-time, are younger than Arendel. An image of Icarus, the previous record holder for the farthest single star he has ever seen. The image on the left shows the huge cluster of galaxies between Earth and Icarus. From NASA: “The panels on the right show the view in 2011, without Icarus being visible, compared to the glow of the star in 2016.” NASA, ESA and P. Kelly (University of Minnesota) Seeing through the gravitational lens The Arendel galaxy, the arc of the East, took its name from this gravitational lens phenomenon that made this discovery possible. “This galaxy appears to be magnified and stretched into a long, slender crescent shape due to the gravitational effect of a huge cluster of galaxies in the foreground,” said Brian Welch, an astronomer at Johns Hopkins University and lead author of Nature. Welch told The Verge that he crashed into Earendel while studying the gravitational lens itself. Gravitational lenses, like magnifying glasses, tend to distort and rotate images and have higher and lower magnification areas. If you have a magnifying glass at home, the best magnification is probably in the center of a simple circle. Gravitational lenses are more difficult to use. Gravitational lenses, like magnifiers, tend to distort and rotate images and have higher and lower magnification areas. In a gravitational lens, there is a line called the “critical curve” where the magnification is more pronounced. Objects seen through the lens are reflected throughout the critical curve, appearing many times. And the closer they align with the curve line from our point of view on Earth, the more they magnify. “I was creating a model of galaxy cluster lens effects to measure the magnification of the arc of the sunrise,” Welch said. “Models have continued to predict that this one bright spot on the arc should have extremely high magnification.” Welch realized that this bright spot was an object very closely aligned with the critical curve – so close and so small that even Hubble’s sharp eye could see its double, reflected image across the line as a single spot. This proximity to the critical curve also meant that whatever it was, it had already magnified somewhere between 1,000 and 40,000 times before it reached Hubble. As small as it looked on Hubble, it was actually much smaller – tiny on the scale of the Sunrise Arc galaxy. “As I searched more, I found that the source was too small to be anything other than a single star (or binary system),” Welch said. The ancient universe Welch and a large international team of co-authors spent three and a half years studying Earendel in multiple Hubble observations to confirm that they saw something real rather than a transient phenomenon of light. That time and effort was worth it, Welch said, because these very old stars can teach us things about the history of the universe. “With distant objects, we see the past of the universe at a time when the universe looked very different from what it looks like today,” Welch said. “We know that galaxies look different in this early age and we know that there were relatively few generations of stars that came before.” “With distant objects, we see the past of the universe and the time when the universe looked very different from today.” Stars are the factories of heavy elements in our universe, formed when lighter atoms such as hydrogen and the sun fuse through nuclear fusion to form heavier material such as carbon, oxygen and even iron. Earendel, at that early stage in the history of our universe, probably had very little material heavier than helium in its system, Welch said. “Detailed study of this star with a lens gives us a new window into what the stars were like in those early days and how they differ from the stars in the nearby universe,” Welch said. The James Webb Space Telescope (JWST), launched in December 2021, is currently being prepared for scientific operations. His vision, clearer than that of Hubble, should be able to confirm their conclusion that Earendel is a single stellar system and not a cluster of stellar systems assembled, the authors wrote in the paper. They also hope to see if Earendel was a solitary star or a binary system, learn more about the star’s temperature and mass, among other properties. JWST will be busy making its way through a scientific wish list that has grown a lot over the years astronomers have been waiting for the launch, as previously reported by The Verge. This will include the study of exoplanets as well as the ancient universe – including stellar systems such as Earandel that glowed at dawn.
