EarthSky’s Will Triggs explains what’s so surprising about the discovery of oxygen in the most distant known galaxy.
Most distant known galaxy is mature in a baby universe
In 2024, the James Webb Space Telescope spotted the most distant galaxy we’ve yet seen. It’s named JADES-GS-z14-0, and we’re seeing it back in the Cosmic Dawn, when the universe was just 2% of its current age. And on March 20, 2025, two teams of astronomers said they’ve detected oxygen in this galaxy. This was a surprise, because – based on our current understanding of how the universe developed – stars shouldn’t have been evolved enough to produce heavy elements like oxygen that early in the universe.
One team published their peer-reviewed results in the journal Astronomy & Astrophysics on March 20, 2025. And the other team published their peer-reviewed results on the same day in The Astrophysical Journal.
Early universe, older stars
We see JADES-GS-z14-0 as it was 13.4 billion years ago, because that’s how long its light takes to reach us. The universe itself was just around 300 million years old at that time, or about 2% of its current age. This is a time period we call the Cosmic Dawn.
But the astronomers were surprised to find oxygen in this galaxy. Heavier elements, like oxygen, spread throughout a galaxy after the star dies and blows itself apart. So for stars to have spread oxygen in the galaxy, there must have already been a generation of them that lived and died. Young stars are made mostly of hydrogen and helium, so that’s what we’d expect to find in a galaxy at this time. Instead, the new studies show that JADES-GS-z14-0 has around 10 times more heavy elements than they thought possible. Therefore, astronomers have to rethink their ideas of how stars and galaxies lived and died in the early universe.
Lead author of the paper in the The Astrophysical Journal, Sander Schouws of Leiden Observatory in the Netherlands, said:
It is like finding an adolescent where you would only expect babies. The results show the galaxy has formed very rapidly and is also maturing rapidly, adding to a growing body of evidence that the formation of galaxies happens much faster than we expected.
A surprise finding
Lead author of the paper in the journal Astronomy & Astrophysics, Stefano Carniani of the Scuola Normale Superiore of Pisa, Italy, said:
I was astonished by the unexpected results because they opened a new view on the first phases of galaxy evolution. The evidence that a galaxy is already mature in the infant universe raises questions about when and how galaxies formed.
In addition, the detection of oxygen allows astronomers to make precise distance measurements for the galaxy. Co-author of the paper in Astronomy & Astrophysics, Eleonora Parlanti of the Scuola Normale Superiore of Pisa, said:
The ALMA detection offers an extraordinarily precise measurement of the galaxy’s distance down to an uncertainty of just 0.005%. This level of precision — analogous to being accurate within 5 cm over a distance of 1 km — helps refine our understanding of distant galaxy properties.
Bottom line: Astronomers have discovered oxygen in the most distant known galaxy. The finding was a surprise, because it means the stars within are older than we would expect in the early universe.
Source: The eventful life of a luminous galaxy at z = 14: metal enrichment, feedback, and low gas fraction?
Source: Detection of [OIII]88µm in JADES-GS-z14-0 at z=14.1793
Via ESO