Since entering service in 2022, the James Webb Telescope has revealed many surprises about the universe in its early stages. Now, another surprise can be added, which is the observation of a galaxy that was already “dead” when the universe was only five percent of its current age.
Scientists said that the telescope observed a galaxy that actually stopped forming stars about 13.1 billion years ago. Many dead galaxies have been observed over the years, but these are the oldest, at about 500 million years.
“It appears that the galaxy lived a fast and violent life and then stopped forming stars very quickly,” said Tobias Loser, an astrophysicist from the Kavli Institute of Cosmology at the University of Cambridge, and the lead author of the study published in the scientific journal Nature.
He added: “For the first few hundred million years of its history, the universe was violent and active, and gas was abundant to fuel the process of star formation in galaxies. That makes this discovery very puzzling and interesting.”
After galaxies stop forming stars, they become a bit of a stellar graveyard.
“Once star formation ends, existing stars die and are not replaced,” said Francesco Di Eugenio, an astrophysicist at the Kavli Institute. “This happens in a hierarchical manner, arranged according to stellar weight, because the most massive stars are the hottest and brightest, and as a result they are the shortest-lived.” .
Di Eugino added: “As the hottest stars disappear, the color of the galaxy changes from blue, which is the color of hot stars, to yellow and then red, which is the color of smaller stars.”
He continued: “Stars with the mass of the Sun live for about ten billion years. If this galaxy had stopped forming stars at the time we observed it, there would be no Sun-like stars left in it at the present moment. But stars much smaller than the mass of the Sun could live for trillions of years. “So they can continue to shine long after star formation stops.”
