A Remarkably Tight Cluster of Protostars Likely Discovered

We may have finally observed the first generation of stars. After decades of searching for these pristine giants, known as Population III stars, astronomers have found their most promising candidate yet.

Population III stars are anticipated to be markedly distinct from today’s stars, or Population I stars. They are believed to have formed from pure hydrogen and helium gases before supernovae and powerful stellar winds dispersed heavier elements across the universe. These stars are also predicted to be larger and hotter than modern counterparts.

That’s precisely the case, according to Eli Visbal. Researchers from the University of Toledo in Ohio made this discovery through a detailed examination of prior James Webb Space Telescope (JWST) observations of a distant galaxy known as LAP1-B. With a redshift of 6.6, this galaxy is visible approximately 800 million years after the Big Bang. Its discovery was facilitated by the magnification of its light due to gravitational lensing by nearby galaxy clusters.

“There’s likely much more to discover in the universe, but we can only see it illuminated by this expanding star cluster,” Visbal noted. When his team estimated how many Population III clusters could exist at this redshift, they figured there should be only one—exactly what they observed. “Our abundance calculations aligned perfectly with those of the previous research team,” he added.

Another advantage of LAP1-B is that it contains only enough stars to comprise several thousand times the mass of the Sun. In contrast, other Population III galaxy candidates usually have significantly larger stellar masses, which do not align with simulations of Population III cluster formation. “This is the most robust candidate we’ve encountered,” says Visbal.

Most Population III stars are thought to have existed and perished between about 100 million and 400 million years after the Big Bang, at which point there were enough heavy elements in the universe to create stars similar to those we observe today. “This object meets many criteria, but I remain somewhat skeptical because these stars emerge later in the timeline, and there may be other viable explanations,” remarks Ralph Cressen from the University of Heidelberg, Germany. “Discovering Population III clusters would be fascinating, but statistically, this would surely be an anomaly.”

However, primordial pockets of hydrogen and helium could linger longer, potentially leading to the formation of Population III stars, as Visbal suggested.

“LAP-B1 is a particularly intriguing candidate, but we are still far from the clear and undeniable indications we would need for definite identification of Population III,” comments Roberto Maiorino at Cambridge University. “[For these to truly be Population III stars] it requires an extremely fortunate combination of factors, each of which is quite rare on its own, and even rarer when they occur together. Further observations and in-depth simulations are essential to ascertain whether LAP1-B represents the first detection of these enigmatic stars.

Understanding Population III stars is crucial, as they offer insights into the formation of the universe’s first heavy elements. “They reveal how the universe’s chemistry evolved from being solely hydrogen and helium to the diverse range of chemicals, life, and entities that exist today,” Visbal states. The stars of Population III were the pioneering building blocks of the complexity encompassing us now.