Hubble reveals the most distant star ever discovered

The farthest star – or perhaps a pair of stars – that astronomers have ever seen has just been revealed thanks to the Hubble telescope and a huge cluster of galaxies. Far from Earth, the universe curves around the bulk of the galaxy cluster, creating a gravitational lens in spacetime much like the curved lens in a magnifying glass. Like a magnifying glass, it revealed something small and subtle: a star system from the early universe.

The distant star system takes the official name WHL0137-LS, but the astronomers who found it called it “Earendel” from the Old English word for “morning star” or “rising light”.

The Earendel system as we see it today was shining in just 900 million years from the Big Bang, according to the authors New paper in the magazine nature describing the discovery. 12.8 billion years passed before the light reached the Hubble Space Telescope, amplified by a lucky gravitational trick to appear as a tiny smudge of photons on the Hubble image sensor. Earndel 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 old stars, Earndel stands out: astronomers note the previous record holder, nicknamed Icarus, as it appeared 9.4 billion years ago – 3.4 billion years more recently than the new record holder. Even the oldest known supernovae, which are usually the brightest and most easily observed for individual objects across the massiveness of spacetime, are smaller than Earndel.

Seeing through the lens of gravity

The main Earndale galaxy, the sunrise arc, derives its name from the gravitational reversal effect that made this discovery possible.

Brian Welch, an astronomer at Johns Hopkins University and lead author of nature paper.

Welch said the edge It was found by Earndel while studying the same gravitational lens.

Gravitational lenses, like magnifying lenses, tend to warp and warp images and have higher and lower magnification areas. If you have a magnifying glass at home, it is likely to be the best magnification In the middle of a simple circle. Gravity lenses are more difficult to use.

In a gravitational lens, there is a line called the “critical curve” where the magnification is most intense. Objects seen through the lens are reflected across the critical curve, and appear multiple times. The closer they are to the curve line from our perspective on Earth, the more they are amplified.

Science: NASA, ESA, Brian Welch (JHU), Dan Koe (STScI); Image processing: NASA, ESA and Alyssa Pagan (STScI)

“I was creating a lens effects model for a cluster of galaxies, with the goal of measuring the magnification of the sunrise arc,” Welch said. “Models have been predicting that this bright spot on the arc must have an extremely high magnification.”

Welch realized that this bright spot was something closely aligned with the critical curve—so close and so small that Hubble’s sharp eye managed to resolve its double image reflected across the line as a single stroke. This proximity to the critical curve also means that whatever it was, it was already magnified somewhere between 1,000 and 40,000 times before reaching Hubble. As small and faint as it seemed to the Hubble telescope, it was actually much smaller—small on the scale of the Sunrise Arc Galaxy.

“The more I looked into it, the more I found that the source was too small to be anything other than a single star (or binary system),” Welch said.

ancient universe

Welch and a large international team of co-authors spent three and a half years studying Earndale through various Hubble observations to confirm that they were seeing something real and not a passing effect of light.

Welch said the time and effort was worth it, because these old stars can teach us about the history of the universe.

“With objects far away, we see the past of the universe and to a time when the universe looked very different from what it is today,” Welch said. “We know that galaxies look different at this early time, and we know that there were relatively few generations of stars that came before.”

Stars are the factories of heavy elements in our universe, formed when lighter atoms like hydrogen and helium fuse together through nuclear fusion to form heavier matter like carbon, oxygen and even iron. Welch said that Earndale, at that early point in our universe’s history, may have had very little material heavier than helium in its system.

“Studying this lensed star in detail gives us a new window into what stars looked like in these early days and how they differ from stars in the nearby universe,” Welch said.

The James Webb Space Telescope (JWST), which was launched in December 2021, is currently preparing for scientific operations. In the paper, the authors write that his optics, more visible than Hubble’s, should be able to confirm their conclusion that Earendel is a single star system rather than a group of star systems all grouped together. They also hope to learn whether Earendel is a single star or a binary system, and learn more about the star’s temperature and mass, among other properties.

JWST will be busy working its way through a science wish list that has grown so long in the years astronomers have spent anticipating the launch, as the edge Previously mentioned. This will include the study of exoplanets as well as the ancient universe – including star systems such as Erandel that glowed at the dawn of history.

Update 12:07 PM ET: This article has been updated with an additional image of Erandel and the Sunrise Arch.