In a galaxy that existed just 900 million years after the Big Bang, the primordial star Eärendel has been imaged by the NASA/ESA Hubble Space Telescope and could offer us a rare window into the early universe as the most distant star never found by astronomers.
Gravitational lenses
Despite being one of the largest stars ever observed, its distance from Earth made it clear that Eärendel was not easily observable, even with the huge Hubble telescope.
However, a team from the Max Planck Institute in Germany has been able to detect the dim light of the star thanks to a cluster of galaxies that are between it and Earth, and that has made it possible to ‘create’ a powerful natural magnifying glass , which distorts and amplifies the light from distant objects behind. Gravitational lenses act like lenses that focus sunlight.
“This is one of the Hubble Space Telescope’s major discoveries in its 32 years of observation,” said Rogier Windhorst, an astronomer at Arizona State University and co-author of the study.
Located 12.9 billion light-years away in the constellation Cetus – close to the star Mira – the star creates an “extraordinary new benchmark” in our understanding of the evolution of the universe and the first stars that formed after this Big Bang.
Eärendel, “morning star” or “rising light” (inspired by the poem Eärendel’s Journey by author JRR Tolkien), could be between 50 and 500 times more massive than our Sun and millions of times brighter , according to published by the authors in their study that collects the journal Nature and that covers the covers of the media around the world. Future follow-up observations with NASA’s James Webb Space Telescope (JWST) should help confirm whether the detected object ultimately turns out to be a star or something else entirely.
“With James Webb, we will be able to confirm that Earendel is indeed just a star and, at the same time, quantify what kind of star it is,” said Sune Toft, leader of the Cosmic Dawn Center and professor at the Niels Bohr Institute in Copenhagen. “Webb will even allow us to measure its chemical composition. Potentially, Eärendel could be the earliest known example of the first generation of stars in the universe.”
early years of the universe
Eärendel existed shortly after the infant universe emerged from an age of darkness , when some of the earliest galaxies were growing and evolving.
“As we observe the cosmos, we also look back in time, so these extremely high-resolution observations allow us to understand the building blocks of some of the earliest galaxies,” explains Victoria Strait, co-author of the study.
The star no longer exists, having exploded millions of years ago, but its light was so powerful that it is still visible and detected by the unbeatable Hubble Space Telescope.
“When the light we see from Eärendel was emitted, the universe was less than 1 billion years old, only 6% of its current age. At the time it was 4 billion light-years from the proto-Milky Way, but during the nearly 13 billion years it took for light to reach us, the universe has expanded so that it is now a staggering 28 billion light-years away. million light years away.
Icarus is no longer the farthest
This discovery unseats the star Icarus from first place, which since 2018 had the honor of being the farthest observed to date. Icarus was also captured by Hubble at 9 billion light years.
Is Eärendel a Population III star ? (pure hydrogen and helium stars, the first to appear after the Big Bang). We’ll have to wait for Webb to work at full capacity to find out.
Referencia: Welch, B., Coe, D., Diego, J.M. et al. A highly magnified star at redshift 6.2. Nature 603, 815–818 (2022). https://doi.org/10.1038/s41586-022-04449-y
