We may have found a surprisingly nearby cluster of primordial stars

We may have finally seen the first generation of stars. Astronomers have been searching for these primordial monsters, called Population III stars, for decades. Now they have found perhaps their most promising candidate yet.

Population III stars They are expected to be very different from modern, or Population I stars. They may have formed from pure hydrogen and helium before heavier elements were spread throughout the universe by supernovae and powerful stellar winds. They are expected to be larger and hotter than modern stars.

That's exactly what Eli Visbal from the University of Toledo in Ohio and his colleagues discovered this when they conducted a detailed analysis of previous James Webb Space Telescope (JWST) observations of a distant galaxy called LAP1-B. Its redshift (the number that astronomers use to measure distance) is 6.6, which means we see LAP1-B as it was about 800 million years after the Big Bang. It's so far away that the only reason we could detect it at all is because its light was amplified by a closer cluster of galaxies in a process called gravitational lensing.

“There should be tons and tons of them throughout the observable universe, but we can only look under the lamppost of this cluster, which magnifies the light,” says Visbal. When he and his team calculated how many Population III star clusters we should find at this redshift, they found that it should be around one – which is exactly what they saw. “Our population estimate is entirely consistent with [the previous research team] found the one where they did it,” he says.

Another argument in favor of LAP1-B is that it appears to have enough stars to be several thousand times the mass of the Sun. Other Population III galaxy candidates tend to have much higher stellar masses, inconsistent with modeling of how clusters Population III stars form. “This is the best candidate at the moment,” says Visbal.

Most Population III stars are expected to have lived and died about 100–400 million years after the Big Bang, after which they would have been abundant. heavy elements in space to form stars more similar to those we see today. “This object meets many of the criteria, but I'm a little skeptical about it because these stars are already late in their appearance and there may be alternatives that can also do the job,” says Ralph Klessen at the University of Heidelberg in Germany. “It would be very interesting to see the Population III star cluster, but statistically it would certainly be an outlier.”

However, it is possible that pockets of pure hydrogen and helium could survive longer and later form Population III stars, Visbal says.

“LAP-B1 is an extremely interesting candidate, but it is still far from the clear and unambiguous signatures we expect for pure population III detection,” says Roberto Maiolino at Cambridge University. “[For these to be Population III stars]it must be an extremely fortunate combination of various factors, each of which is extremely rare in itself, and much rarer when they happen to occur together.” Deeper observations and more detailed modeling will be needed to figure out for sure whether LAP1-B is the first time we've seen these strange stars.

This is important because understanding Population III stars is critical to figuring out how and when the first heavy elements formed. “They can tell us how the chemistry of the universe evolved from just hydrogen and helium to all the cool chemistry and life and everything we have in the universe today,” says Visbal. Population III stars were the first building blocks of the complexity that surrounds us today.