Images taken by NASA’s James Webb Space Telescope
Astronomers have achieved a groundbreaking feat after identifying 44 individual stars in a galaxy nearly 6.5 billion light-years away.
This remarkable discovery, made possible by and the phenomenon of gravitational lensing, sets a new record for the largest number of individual stars detected in the distant universe.
The findings, led by Fengwu Sun, a postdoctoral researcher at the Center for by Harvard & Smithsonian, and published in Nature Astronomy, open new avenues for studying the universe’s most profound mysteries, including dark matter.
Looking for individual stars in billions of light-years away has long been considered impossible, as these far-flung galaxies typically blur into a diffuse glow.
However, a natural magnification effect called gravitational lensing, coupled with JWST’s infrared capabilities, has changed the game, .
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Gravitational lensing occurs when a massive object, such as a galaxy cluster, bends and amplifies the light of objects behind it.
In this case, the cluster Abell 370 acted as a lens, magnifying a galaxy called the Dragon Arc.
This effect stretched the Dragon Arc into an elongated shape, making individual stars within it visible to JWST’s sensitive instruments.
“When we processed the data, we realized that what appeared to be individual star points were actually stars within this distant galaxy,” said Sun.
Many of the stars identified in the Dragon Arc are red supergiants, a type of massive star in the final stages of its life.
These stars, cooler and more luminous than the blue supergiants often observed in earlier studies, were detectable thanks to JWST’s ability to observe infrared wavelengths.
This marks a shift from earlier discoveries with the Hubble Space Telescope, which had identified only a handful of stars in distant galaxies, most of them blue supergiants like Rigel and Deneb.
“We now have the capability to resolve stars that were previously beyond our reach,” said Sun.
“This discovery provides unprecedented insights into stellar populations and their role in galaxy evolution during the early universe.”
NASA’s James Webb Space Telescope was able to capture images of individual stars on the Abell 370
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Beyond cataloging stars, this discovery has profound implications for the study of dark matter, the invisible substance thought to make up most of the universe’s mass.
Observing how stars are distributed and behave in gravitationally lensed galaxies can reveal information about the structure and composition of the lens itself, offering clues about dark matter.
“This is a significant step forward,” said Yoshinobu Fudamoto, lead author and assistant professor at Chiba University in Japan. “To study stellar populations meaningfully, we need observations like these, with many individual stars resolved.”
This record-breaking observation is just the beginning. Future JWST studies of the Dragon Arc and other lensed galaxies could capture hundreds of individual stars, providing deeper insights into early galaxy formation and the evolution of stellar populations.
Sun is particularly eager to continue exploring red supergiants in distant galaxies. “We can use what we know about nearby red supergiants to interpret what happens next for these stars in the early epochs of the universe,” he said.