In an accomplishment that pushes the boundaries of astronomical observation, scientists have identified more than 40 individual stars in a galaxy nearly 6.5 billion light-years away, marking an unprecedented glimpse into the stellar population of the early universe.
The discovery, which shatters previous records of distant stellar observation, was made possible by NASA’s James Webb Space Telescope (JWST) and a cosmic phenomenon known as gravitational lensing. The observed galaxy, nicknamed the “Dragon Arc,” exists at a time when the universe was just half its current age.
Published in Nature Astronomy, the findings represent a quantum leap forward in our ability to study distant stellar populations. “This groundbreaking discovery demonstrates, for the first time, that studying large numbers of individual stars in a distant galaxy is possible,” says Fengwu Sun, a postdoctoral researcher at the Center for Astrophysics | Harvard & Smithsonian (CfA) and co-author of the study.
The discovery was made while researchers were examining JWST images of the Dragon Arc galaxy, which appears stretched and magnified by the massive Abell 370 galaxy cluster lying between it and Earth. This gravitational lensing effect, predicted by Einstein’s theory of general relativity, acts like a natural cosmic telescope, magnifying distant light by factors of hundreds or even thousands.
Lead study author Yoshinobu Fudamoto, an assistant professor at Chiba University in Japan, explains the significance: “To us, galaxies that are very far away usually look like a diffuse, fuzzy blob. But actually, those blobs consist of many, many individual stars. We just can’t resolve them with our telescopes.”
The newfound stars aren’t just any stellar objects – many are red supergiants, similar to the famous star Betelgeuse in our own galaxy’s neighborhood. This finding marks a departure from previous distant stellar discoveries, which typically identified blue supergiants. The difference highlights JWST’s unique capabilities in infrared observation, allowing it to detect cooler, redder stars that previous telescopes might have missed.
“When we discovered these individual stars, we were actually looking for a background galaxy,” Sun reveals. “But when we processed the data, we realized that there were what appeared to be a lot of individual star points. It was an exciting find because it was the first time we were able to see so many individual stars so far away.”
The discovery has implications beyond mere stellar census-taking. These observations could provide new insights into dark matter, one of the universe’s most enigmatic components. By studying how the gravity of invisible dark matter affects the apparent positions and brightnesses of these distant stars, astronomers hope to better understand its distribution and properties.
Looking ahead, researchers expect future JWST observations to reveal even more stars within the Dragon Arc galaxy. Such observations could eventually lead to detailed studies of hundreds of stars in distant galaxies, providing unprecedented insight into how galaxies evolved in the early universe.
For Sun, the future holds particular promise for studying these ancient red supergiants. “We can use the knowledge we’ve gained from studying red supergiants in the local universe to interpret what happens next for them at such an early epoch of galaxy formation in future studies,” he notes.
The research represents a significant advance from previous studies with the Hubble Space Telescope, which typically found only around seven stars in similar distant galaxies. This dramatic increase in observable stars opens new possibilities for understanding both stellar evolution and the fundamental structure of the universe itself.