This galaxy is approximately 500 million years old.
Since it became operational in 2022, the James Webb Space Telescope has discovered many surprises about the early days of the universe. We can now add one more – observations of a galaxy that “died” when the universe was only 5% of its current age.
On Wednesday, scientists said Webb had discovered a galaxy where star formation stopped about 13.1 billion years ago, 700 million years after the Big Bang event that created the universe. Many dead galaxies have been discovered over the years, but this is the earliest around 500 million years ago.
In some ways, this galaxy is like the late Hollywood actor James Dean, famous for his “live fast, die young” life story.
“This galaxy appears to be living fast and intense, and then quickly ceases star formation.”
“For the first few hundred million years of its history, the universe was violent and active, with vast amounts of surrounding gas fueling the formation of stars in galaxies. This makes this discovery particularly puzzling and interesting,” Luther added.
This galaxy is relatively small, with approximately 100 million to 1 billion stars. This would put it somewhere near the mass of the Small Magellanic Dwarf Galaxy near the Milky Way, although the galaxy is still forming new stars.
When a galaxy stops forming new stars, it becomes something like a stellar graveyard.
“Once star formation ends, existing stars die and are not replaced. This happens in a layered manner in order of stellar weight, as the most massive stars are the hottest, brightest and therefore have the shortest lifespans,” Card said study co-author Francesco De Eugenio, an astrophysicist at the Wiley Institute.
“As the hottest stars die, the color of the galaxy changes from blue (the color of hot stars) to yellow to red (the color of the least massive stars),” De Eugenio added. “Mass and Stars the size of our Sun last about 10 billion years. If this galaxy had stopped forming stars by the time we observe it, there would be no Sun-like stars in it today. However, stars far less massive than the Sun can live for trillions of years years, so they continue to shine long after star formation has ceased.”
The researchers determined that the galaxy experienced a burst of star formation that lasted 30 to 90 million years before suddenly stopping. They are trying to find out why.
They say this could be due to the action of the supermassive black hole at the center of the Milky Way or a phenomenon called “feedback” – an explosion of energy from newly formed stars – pushing the gas needed to form new stars out of the galaxy.
“In addition, the gas may be quickly consumed by star formation and cannot be replenished by fresh gas around the galaxy in time, leading to starvation of the galaxy,” Luther said.
NASA’s Webb telescope is able to see to greater distances and therefore further back in time than its predecessor, the Hubble Space Telescope. Among other discoveries, Webb allowed astronomers to see the earliest known galaxies, which are larger and more numerous than expected.
In the new study, researchers were able to observe dead galaxies at one point in time. They say it’s possible that it later resumed star formation.
“Some galaxies may experience a renaissance if they can find fresh gas to convert into new stars,” De Eugenio said. “We don’t know the ultimate fate of this galaxy. It may depend on what mechanism causes star formation to cease.”
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)
