The researchers looked at the halo of gas around the outskirts of the galaxy, where they believe Pop III stars may have formed. And in GN-z11, they believe they’ve found their long-sought-after signature. So, those are the signs scientists have been looking for-very, very old and very low metallicity. They would have been truly massive, and likely would not have lived very long (on star timescales at least) before exploding in the supernovas that researchers believe seeded the entire rest of the universe with metals. Pop III stars are believed to be made almost entirely of hydrogen and helium-very low metallicity. So, if Pop II needed more metals than the Big Bang could provide, they must have made use of the remnants of Pop III stars. But Pop II stars had to get their start from older stars, as they have more metals than would have been available just after the Big Bang, but less than Pop I. The Pop I stars currently littering the universe were made from the debris left behind when Pop II stars exploded. Heavy elements, by and large, are created by stars-whether it be through fusion in their inner layers or in the moments of intense heat when they go supernova. This is because the populations-as-generations idea is a little bit more literal than just a metaphor. Pop I have the highest metallicities, and Pop III have the lowest. The metals contained within and burned by a star are how we categorize these celestial furnaces into their respective populations. So, in space terms, metals are just any sufficiently heavy elements.) (Important caveat: astronomers call anything heavier than hydrogen or helium a metal. The other is a property of stars called metallicity-the amount of metals a star has. The team used the telescope to spy on GN-z11, a bright, really-far-away galaxy, in the hopes of getting a strong and clear spectrum from when the universe was only about 400 million years old (today, it’s around 13.7 billion years old). Because light has a finite speed, the further away you look, the further back in time you can see. The paper was uploaded to the preprint database arXiv, and has yet to be peer-reviewed. An international team just announced in a new paper that they have found the first evidence of Pop III stars with the help of JWST. Technically, we don’t know for sure that they ever existed. Think of it more like generations-if Pop I are the equivalent of Gen Z stars, Pop III are the boomers. Our Sun is a Pop I star.Ĭrucially, this has nothing to do with how far along a star is in its individual life cycle. Pop III are the oldest stars, Pop II are in the middle, and Pop I are the newest. Researchers call them Population III (or Pop III) stars, because sometimes astronomers name things in reverse for some reason. But the search for these stars has been long and fruitless for many, many years. It’s something that you’d think we’d have seen by now, considering how far Hubble has been able to look back in time for decades. The James Webb Space Telescope (JWST) may have just found the first stars in the universe.
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