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New Discovery of Individual Stars in the Distant Universe
In a remarkable feat of astronomical observation, an international team of researchers has successfully identified individual stars in a galaxy located approximately 6.5 billion light-years away from Earth. This discovery was made possible using NASA’s James Webb Space Telescope (JWST) and takes place at a time when the universe was merely half its current age.
The lead researcher, Fengwu Sun, a postdoctoral fellow at the Center for Astrophysics | Harvard & Smithsonian (CfA), and his team detected 44 individual stars within this distant galaxy, a record that underscores the capabilities of the JWST. The breakthrough stems from the phenomenon known as gravitational lensing, where the intense gravitational pull of massive galaxy clusters bends and amplifies light from more distant stars, allowing them to be observed with unprecedented clarity.
This significant finding, detailed in a recent publication in Nature Astronomy, not only represents the highest count of stars discovered in the distant universe but also provides a new avenue for exploring dark matter—one of the universe’s most elusive components.
“This groundbreaking discovery demonstrates, for the first time, that studying large numbers of individual stars in a distant galaxy is possible,” stated Sun, who also contributed to the study. “Previous studies using the Hubble Space Telescope identified only a few stars. Our current capabilities allow for the resolution of stars that eluded earlier observations, enabling deeper insights into dark matter and its interactions within these galaxy clusters.”
The Role of Gravitational Lensing
The galaxy in which these stars were found is part of a structure known as the Dragon Arc, located behind the Abell 370 galaxy cluster, which acts as a powerful gravitational lens. The gravitational influence of Abell 370 distorts and magnifies the light from the Dragon Arc, creating an effect reminiscent of a cosmic funhouse mirror.
Upon analyzing the light from the stars in the Dragon Arc, the researchers found that many of them were red supergiants, akin to Betelgeuse in our own Milky Way. This finding is a shift from earlier observations that predominantly identified blue supergiants, such as Rigel and Deneb. The ability to observe lower-temperature stars in infrared light speaks to the advanced technology of the JWST.
“Initially, we were focused on identifying a background galaxy that was being magnified,” explained Sun. “However, our data processing revealed many individual star points. It was exhilarating to witness so many individual stars from such a vast distance.”
Future Prospects for Red Supergiants
Sun expressed particular enthusiasm for studying the red supergiants further. “Our local understanding of red supergiants is deep, primarily because they are closer and easier to observe in detail. By applying this knowledge, we can gain insights into the evolutionary paths of these massive stars during the early stages of galaxy formation.”
Stars within the universe typically congregate in vast numbers; for instance, both the Milky Way and Andromeda galaxies boast tens of billions of stars. However, observing individual stars in galaxies billions of light-years away has traditionally proven difficult because their light merges into indistinct blobs due to the immense distances involved.
“From our perspective, these distant galaxies often appear as diffuse, fuzzy entities,” noted Yoshinobu Fudamoto, assistant professor at Chiba University and lead author of the study. “Yet, these smudges are comprised of many individual stars that we cannot resolve with traditional telescopes.”
Advancements through Gravitational Lensing
Recent advancements in astronomical techniques have harnessed gravitational lensing to magnify the visibility of remote stars. Albert Einstein’s theory predicted that significant gravitational fields could distort light, allowing distant objects to be observed far more clearly than previously possible. This discovery shifts the landscape of astrophysical research, unveiling the potential to study stellar populations with statistical significance.
The research team anticipates that upcoming JWST observations will uncover even more stars in the Dragon Arc, paving the way for detailed studies of these celestial bodies. Such observations could enhance our understanding of gravitational lens structures and contribute to unraveling the mysteries surrounding dark matter.
More information: Yoshinobu Fudamoto et al, Identification of more than 40 gravitationally magnified stars in a galaxy at redshift 0.725, Nature Astronomy (2025). DOI: 10.1038/s41550-024-02432-3
Source
phys.org