Traits of ancient galaxy 25 billion light-years away revealed.

The James Webb Space Telescope has identified GS-9209, the earliest known quiescent galaxy, which formed 600 to 800 million years after the Big Bang and stopped producing stars half a billion years later. Despite being smaller than the Milky Way, it contains a similar number of stars and a central supermassive black hole five times larger than anticipated, which may have halted star formation by emitting high-energy radiation that drove out galactic gas. The discovery could explain why GS-9209 stopped forming new stars.