Star was imaged using the Hubble telescope in 2016, when it got a lucky boost from nature
Scientists have captured an image of the most distant individual star ever spotted — one that is nine billion light years away or 100 times farther away than the previous record-breaker. (Not including extremely bright exploding stars called supernovas).
The star is a blue supergiant nicknamed Icarus, possibly hundreds of thousands of times brighter than the sun. The light in the image left the star when the universe was just five billion years old. The universe’s current age is estimated at 13.8 billion years.
The record-breaking portrait was captured by the Hubble space telescope. Powerful as Hubble is, it normally wouldn’t have been able to see even a star this bright so far away.
But Hubble itself was lucky enough to view the star through a temporary “natural telescope” — a phenomenon called gravitational lensing, reported an international team of astronomers in the journal Nature Astronomy today.
Gravity from massive galaxy clusters can sometimes act as a lens in space, bending and magnifying the light of objects behind them.
In this case, scientists think a massive star from a galaxy cluster called MACS J1149+2223, about five billion light years from Earth, temporarily passed in front of Icarus, magnifying it and boosting making it appear 2,000 times brighter than normal.
At that moment in 2016, Patrick Kelly, then a postdoctoral researcher at the University of California Berkeley, had been using Hubble to monitor a supernova in the same field of view as Icarus.
He and his team noticed a star that hadn’t been visible before. Further study showed it wasn’t a supernova, as it wasn’t getting hotter or exploding.
“The light is just being magnified,” Kelly said in a statement. “And that’s what you expect from gravitational lensing.”
Kelly is now an assistant professor of physics and astronomy at the University of Minnesota.
While gravitational lensing has been used to spot very distant galaxies, which shine with the light of billions of stars, this is the first time it has been observed magnifying an individual star, the researchers report.
Astronomers have seen galaxies as far away as 13.3 billion light years.