Earliest-known 'dead' galaxy spotted by Webb telescope

The James Webb Space Telescope observes a galaxy that was already “dead” when the universe was only 5% of its current age.

The James Webb Space Telescope since becoming operational in 2022 has uncovered numerous surprises about what things were like in the universe's early stages. We now can add one more - observations of a galaxy that was already "dead" when the universe was only 5% of its current age.

Scientists said on Wednesday that Webb has spotted a galaxy where star formation had already ceased by roughly 13.1 billion years ago, 700 million years after the Big Bang event that gave rise to the universe. Many dead galaxies have been detected over the years, but this is the earliest by about 500 million years.

In some ways, this galaxy is like the late Hollywood actor James Dean, famous for his "live fast, die young" life story.

"The galaxy seemed to have lived fast and intensely, and then stopped forming stars very rapidly," said astrophysicist Tobias Looser of the Kavli Institute for Cosmology at the University of Cambridge, lead author of the study published in the journal Nature.

"In the first few hundred million years of its history, the universe was violent and active, with plenty of gas around to fuel star formation in galaxies. That makes this discovery particularly puzzling and interesting," Looser added.

This galaxy is relatively small, with perhaps 100 million to one billion stars. That would put it in the neighborhood of the mass of the Small Magellanic Cloud dwarf galaxy situated near our Milky Way, though that one is still forming new stars.

After a galaxy stops forming new stars, it becomes a bit like a stellar graveyard.