JWST may have detected the universe’s first stars, formed about 200 million years after the Big Bang in the distant galaxy LAP1-B.
The stars match theoretical Population III traits, being extremely massive, low in metals, and visible due to powerful gravitational lensing.
If confirmed, the finding could unlock new insights into the cosmic dawn, galaxy formation, and the universe’s earliest evolution.
NASA was able to catch a glimpse of the long-elusive “cosmic dawn” as its James Webb Space Telescope (JWST) possibly detected the universe’s oldest star. It is believed to have been formed just after the Big Bang nearly 13.8 billion years ago. The study published in The Astrophysical Journal Letters in late 2025 suggests that astronomers found evidence of the existence of the first generation of stars, called Population III (Pop III), in a distant galaxy known as LAP1-B. The galaxy is located approximately 13 billion light-years away from Earth.
The discovery was a result of JWST’s observation of the “epoch of reionization” period of the galaxy, which is considered a key phase in cosmic history when the universe began transitioning from darkness to light. These stars are believed to have played a central role in ending the universe’s “cosmic dark ages,” as ultraviolet radiation from the first stars and galaxies transformed neutral hydrogen and helium gas into ionized plasma. Upon confirmation, this observation would mark the first-ever evidence of Pop III stars. These ancient stars are extremely rare and are believed to have formed roughly 200 million years after the Big Bang.
Pop III stars have long been considered a missing piece in the cosmic puzzle since humans began studying space. These stars were the first to ignite, forming from primordial gas composed entirely of hydrogen and helium. They are thought to have produced the first heavy elements through nuclear fusion and explosive deaths, which later served as the foundation for the formation of subsequent generations of stars, galaxies, and planetary systems. Spotting these stars would provide deeper insight into the universe’s earliest evolutionary stages and help validate decades of theoretical research.
Infrared spectroscopic observations of LAP1-B by JWST contributed to the evidence, revealing intense ultraviolet radiation consistent with extremely massive stars. Data from the research team led by astronomer Eli Visbal shows that these stars are nearly 100 times the mass of the Sun, a defining theoretical characteristic of Pop III stars.
According to the study, LAP1-B satisfies three key theoretical conditions required for Pop III star formation. The stars formed at suitable temperatures in a low-metallicity environment dominated by hydrogen and helium. The Pop III stars are likely grouped in low-mass clusters containing only a few very large stars, and the cluster satisfies the mathematical requirements of the initial mass function, which governs how stellar masses are distributed at birth.
The potential detection was made possible due to the crucial role of gravitational lensing. JWST was able to visualize the stars because a massive galaxy cluster located between Earth and LAP1-B magnified the distant galaxy’s light by nearly 100 times. Eli Visbal, the team leader from the University of Toledo, said, “If indeed Pop III, this is the first detection of these primordial stars.” The detection was possible due to the combination of Webb’s unprecedented sensitivity and the powerful magnification caused by gravitational lensing.
The new observations and findings align with long-standing theories about the formation of primordial stars. In the early universe, star formation was less fragmented due to the absence of heavier elements such as carbon and oxygen in cosmic gases. This led to the formation of fewer but significantly more massive stars. The researchers confirmed this theory after finding that the stars in LAP1-B are surrounded by gas with minimal metal content and appear to exist in clusters totaling around 1,000 solar masses.
The discovery also contributes to a broader understanding of the universe’s structure beyond stellar formation. According to the standard model of cosmology, Pop III stars formed within small dark matter halos that later merged to create larger galaxies. Studying these stars could therefore offer insight into the earliest stages of galaxy formation and help constrain the properties of dark matter. This, in turn, could lead to predictions about the conditions that enabled the first appearance of such stars under different dark matter models.
Scientists are proceeding with caution, resisting the urge to draw definitive conclusions, as these ancient stars have remained elusive. Pop III stars are extremely distant and exist in small, faint clusters, making them difficult to locate or observe. While the evidence from LAP1-B is strong, the stars’ primordial nature is still under study. The research team now plans to conduct detailed hydrodynamical simulations to examine the transition from Pop III to Pop II stars and test whether the spectrum of LAP1-B and similar objects is consistent with theoretical predictions.
Visbal also noted, “LAP1-B may only represent the tip of the iceberg,” suggesting that this discovery could be just the beginning. Researchers hope to identify more Pop III stars at high redshifts using gravitational lensing techniques. If these early findings are confirmed, JWST could significantly advance understanding of when and how the universe’s first stars formed, offering a glimpse into the moment when the cosmos first lit up.
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