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The galaxy CEERS2-588 flared up like a bonfire fed with an armful of wood all at once. Just 400 million years after the Big Bang, it had already built up a mass of a billion suns and ignited countless stars. But then the fuel ran out, and over the last 10 million years, star formation in it has almost completely ceased.

The James Webb Space Telescope observed this galaxy in the infrared. Ordinary telescopes only see the ultraviolet light of young stars, but spectroscopy on Webb allowed a deeper look — into the optical range, which has shifted to infrared for us due to the expansion of the universe. Where bright hydrogen and oxygen lines were expected, there was only a flat shelf — a sign of old stars that no longer heat the gas around them.

This discovery breaks the usual picture. Previously, astronomers thought that such massive galaxies in the young universe should be star factories. CEERS2-588 shows that some galaxies flared up quickly and died out just as fast. Its chemical composition also surprised: it contains nearly as many metals (as astronomers call all elements heavier than helium) as our Sun. To produce that many metals, you need generations of stars exploding as supernovae. This means the first stars were born and died much faster than previously thought.