We’ve spotted the first stars in a galaxy far away. We know very little about star formation in the early universe simply because we have to look so far away to see it. Looking at objects in the first several hundred million years after the big bang is a stretch even for our best telescopes.
But now, Takuya Hashimoto at Osaka Sangyo University in Japan, and his colleagues have spotted stars that formed just 250 million years after the big bang using the universe’s own magnifying glass.
The galaxy containing these stars is 13.2 billion light years away, further than we can directly look, but it’s visible because its light is being gravitationally lensed by a closer cluster of galaxies. The intense gravity of the cluster bends the light as it passes from the original galaxy towards Earth, creating a magnification effect.
The researchers used four of the world’s most powerful telescopes to look at the galaxy in three different frequency ranges of light. They used spectral signatures of oxygen – the earliest signs of oxygen in the young universe that we’ve ever spotted – to determine the distance to the galaxy.