The James Webb Space Telescope has one of the world’s best spectrographs on board, which it can use to track the chemical composition of distant objects. It has recently learned something incredible about a very distant galaxy.
Rare galaxy
Astronomers at the University of Arizona have found out more about a surprisingly mature galaxy that existed when the universe was just under 300 million years old — just 2% of its current age.
The galaxy called JADES-GS-z14-0, observed by NASA’s James Webb Space Telescope (JWST), is unexpectedly bright and chemically complex for an object from this original epoch, researchers said. It offers a rare chance to peer into the oldest section of the Universe.
The findings, published in the journal Nature Astronomy, are based on the researchers’ previous discovery of JADES-GS-z14-0, the most distant galaxy ever observed, which they reported in 2024. While the first discovery established the galaxy’s record distance and unexpected brightness, this new study delves deeper into its chemical composition and evolutionary state.
“It wasn’t just stumbling across something unexpected,” says Kevin Hainline, co-author of the new study and an assistant professor at Steward University Observatory. The study was deliberately designed to look for distant galaxies, but this galaxy broke all the team’s records – it was extremely bright and had a complex chemical composition that was completely unexpected at such an early stage in the Universe’s history.
“The fact that we found this galaxy in a tiny patch of sky means there must be more of them,” said lead study author Jakob Helton, a graduate student at Stewart Observatory. “If we looked at the whole sky, which we can’t do with JWST, we would eventually find more of these extreme objects.”
Search instruments for primordial galaxies
The research team used several instruments aboard JWST, including the Near Infrared Camera, or NIRCam, whose construction was led by UCLA astronomy professor Marcia Rieke. The telescope’s other instrument, the Mid-Infrared Instrument (MIRI), detected something extraordinary: a significant amount of oxygen.
In astronomy, anything heavier than helium is considered a “metal”. It takes generations of stars to produce such metals. The early Universe contained only hydrogen, helium, and a small amount of lithium. But the discovery of significant amounts of oxygen in the JADES-GS-z14-0 galaxy suggests that the galaxy was forming stars potentially 100 million years before it was observed.
Complex galaxy chemistry and its age
According to George Rieke, professor of astronomy at Regent University and senior author of the study, the galaxy would have had to arise very early to create oxygen because it would have had to form an entire generation of stars. These stars would have evolved and exploded as supernovae to release oxygen into interstellar space from which new stars would have formed and evolved.
The discovery suggests that star formation began even earlier than scientists previously thought, pushing back the timeline when the first galaxies may have formed after the Big Bang.
The observation took approximately nine days of telescope operation, including 167 hours of NIRCam imaging and 43 hours of MIRI imaging focused on an incredibly small area of the sky. Astronomers were fortunate that this galaxy was in an ideal location to observe with MIRI. If they had pointed the telescope even a fraction of a degree in either direction, they wouldn’t have gotten that important mid-infrared data, Helton said.
JADES-GS-z14-0 Galaxy and the Evolution of the Universe
The existence of such an advanced galaxy at such an early stage of cosmic history serves as a powerful test for theoretical models of galaxy formation.
Since people get the opportunity to directly observe and understand the galaxies that existed during the origin of the Universe, this can provide important insights into how the Universe evolved from simple elements to the complex chemistry necessary for life as we know it.
“We’re in an incredible time in astronomy history,” Hainline said. “We’re able to understand galaxies that are well beyond anything humans have ever found and see them in many different ways and really understand them. That’s really magic.”
According to phys.org
