NASA's Hubble Space Telescope has spotted the most distant single star ever detected in outer space.
Light from the star—dubbed Earendel from an Anglo-Saxon word meaning rising light or morning star—took 12.9 billion light-years to reach Earth and formed about 900 million years after the Big Bang. Earendel is 8.2 billion years older than the Earth and sun and 12.1 billion years older than when the first animals appeared on the planet, reports Rafi Letzter for the Verge. Earendel was described in a paper published this week in Nature. The study shines light on the youngest stars gleaming in the cosmos.
"When the light that we see from Earendel was emitted, the universe was less than a billion years old," says study author Victoria Strait, an astronomer at the Cosmic Dawn Center in Denmark, in a statement. "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."
Astronomers suspect that Earendel is even older than Icarus, the previous record-holder detected by Hubble in 2018. Icarus appeared in outer space 9.5 billion years ago, reports Jake Parks for Astronomy.
Officially known as WHL0137-LS, Earendel was detected by chance when a galaxy cluster aligned with the ancient star and was magnified through a phenomenon called gravitational lensing, a statement explains. Gravitational lensing can magnify distant objects when their light bends and travels along the gravitational curvature of the massive object like a galaxy or galaxy cluster, reports Michelle Starr for Science Alert.
As the light from the distant object bends, the far-away object appears distorted or smudged, but it is also duplicated and magnified. After detecting the light, astronomers can pinpoint where the magnified object is. When seeing objects from early in the universe, or cosmic dawn, the smears of detected light are usually galaxies, per Science Alert. The Hubble telescope detected Earendel after homing in on a magnified streak of light boosted by a nearby galaxy.
Within the galaxy, study author Brian Welch, an astrophysicist at Johns Hopkins University, found the primordial star sitting at the top of the lensing critical curve, or where the magnification is most intense, Science Alert reports. Before reaching the Hubble, the star near the critical point was magnified between 1,000 and 40,000 times. The galaxy was dubbed the Sunrise Arc because of the gravitational lensing effect that made it appear as a long crescent shape, the Verge reports.
Astronomers studied Earendel for 3.5 years, using various models to confirm that the star was real and not a fluke effect from another source of light. The astronomers found that the massive star is millions of times brighter than the sun, reports Charles Q. Choi for Space.com. Although Earendel was recently detected, the massive star is long gone and most likely died in a fiery explosion 13 billion years ago, Astronomy reports.
"Given its mass, it almost certainly has not survived to today, as more massive stars tend to burn through their fuel faster and thus explode, or collapse into black holes, sooner," Welch tells Space.com. "The oldest stars known would have formed at a similar time, but they are much less massive, so they have continued to shine until today."
Details, like its exact brightness, mass, temperature, and type of star, remain uncertain, Space.com reports. Estimated to be anywhere from 50 to 500 solar masses, it is possible that Earendel could have been a binary star system instead of a single star, per a statement.
However, scientists plan to make follow-up observations of Earendel with the James Webb Space Telescope (JWST) to analyze the star's infrared light. JWST's more advanced optics may be able to pinpoint if Earendel is a single star or a cluster of star systems, the Verge reports.
"With James Webb, we will be able to confirm that Earendel is indeed just one star, and at the same time quantify which type of star it is," study author Sune Toft, an astrophysicist at the Niels Bohr Institute's The Cosmic Dawn Center, explains in a statement. "Webb will even allow us to measure its chemical composition. Potentially, Earendel could be the first known example of the universe's earliest generation of stars."