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The James Webb Space Telescope picked up radiation from ionized helium — a telltale sign that the early Universe was lit by stars composed only of hydrogen and helium, the very first suns.
Abstract
The James Webb Space Telescope has confirmed the source of ionized helium (HeII) glowing near the galaxy GN-z11, when the universe was just 400 million years old. High-resolution spectroscopy revealed two components whizzing apart at 120 km/s, and the line is astonishingly strong (>20 Å) with no metals in sight. This is the smoking gun of Population III stars—the elusive first stars forged from pure hydrogen and helium. Like an ancient relic, this helium beacon lets us glimpse the dawn of the first cosmic lights.
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400 million years after the Big Bang, the James Webb Space Telescope noticed a bright spot near the galaxy GN-z11 — like a distant lighthouse whose light pushed through the primordial darkness. Splitting the glow into colors, astronomers found a clear line of extremely hot helium, its atoms stripped of electrons by unimaginable heat.
Such a glow is produced only by stars almost entirely made of hydrogen and helium, with no heavy elements — the so-called first generation of stars (Population III). They lived short lives but shone with furious brightness, then exploded, scattering the first specks of carbon and oxygen.
A twist: the spot turned out to be not a single star, but an entire cluster — a collective beacon whose combined brilliance we see. Without these first suns, the cosmos would have remained a sterile sea of hydrogen and helium forever.
🎯 The first generation stars were likely hundreds of times more massive than the Sun and burned out in just a couple of million years — on cosmic timescales, less than a blink of an eye.
