Astronomers have made an extraordinary discovery, spotting 44 stars in a distant galaxy called the “Dragon Arc,” located 6.5 billion light-years away.
Using NASA’s powerful James Webb Space Telescope (JWST) and the phenomenon of gravitational lensing, they’ve opened a window to the universe’s distant past, when it was only half its current age.
Gravitational lensing is a concept from Albert Einstein’s theory of general relativity.
Jacqueline McCleary, a physics professor at Northeastern University, describes it as nature’s way of bending light.
Imagine a stretched rubber sheet—placing a heavy object on it creates a dip. If you roll a marble across, it won’t travel in a straight line but will curve around the dip.
Similarly, massive objects like galaxy clusters warp space-time, bending light as it travels across the universe.
This effect worked like a giant magnifying glass for the Dragon Arc galaxy. A massive galaxy cluster called Abell 370 lies between Earth and the Dragon Arc.
Its gravitational pull bent and focused the light from the distant galaxy, allowing astronomers to see details they couldn’t otherwise observe.
Detecting individual stars in far-off galaxies is typically impossible, as they are too faint and distant. Astronomers can study stars in nearby galaxies like Andromeda or the Milky Way, but farther out, stars blur together. This time, however, gravitational lensing made it possible to spot 44 stars in the Dragon Arc.
What made this discovery even more fascinating was a second layer of lensing called microlensing. Smaller objects, such as free-floating stars in the Abell 370 cluster, acted as additional lenses. As these smaller stars moved in front of the Dragon Arc’s light, they amplified it further, making individual stars on the galaxy’s edge visible.
This double lensing effect has been used before, but only to capture seven stars in distant galaxies. Now, thanks to the JWST and a lucky combination of cosmic circumstances, astronomers have set a record with 44 stars.
“This discovery is like a magical time machine,” McCleary explains. “It shows us what star formation looked like when the universe was much younger.”
The findings could spark a wave of new research. Scientists are likely to revisit existing JWST data to search for more stars using similar techniques.
“This number could grow quickly,” McCleary says. “We might soon find hundreds of stars in more galaxy clusters, revealing even more about the universe’s history.”
By combining advanced technology with the natural magnification of gravitational lensing, astronomers are uncovering secrets of the cosmos, one distant star at a time.
Source: Northeastern University.
