An unexpectedly bright and chemically complex primordial galaxy from the first 300 million years of the universe’s existence has been discovered by University of Arizona astronomers.
The JADES-GS-z14-0 galaxy is so ancient that it has existed for 98% of the universe‘s lifespan. First reported in 2024, new research into the galaxy’s chemical composition and evolutionary state is challenging existing galaxy formation models.
JADES Views a Primordial Galaxy
NASA’s James Webb Space Telescope (JWST) captured a rare glimpse of this early galaxy during the JWST Advanced Deep Extragalactic Survey (JADES). JADES dedicated over a month of mission time in JWST’s first cycle, focusing on the Hubble Deep Field (GOODS-N) and the Hubble Ultra Deep Field (GOODS-S). While University of Arizona researchers intentionally surveyed distant galaxies, this particular discovery was so unusual that it caught the team off guard.
“It’s not just a tiny little nugget. It’s bright and fairly extended for the age of the universe when we observed it,” said co-author Kevin Hainline of the University of Arizona Steward Observatory.
“The fact that we found this galaxy in a tiny region of the sky means that there should be more of these out there,” said lead author Jakob Helton, a Steward Observatory graduate researcher. “If we looked at the whole sky, which we can’t do with JWST, we would eventually find more of these extreme objects.”
Investigating Primordial Star Formation
Astronomers used several JWST instruments to observe the primordial galaxy, including the Near Infrared Camera (NIRCam) and the Mid-Infrared Instrument (MIRI). The team focused on a narrow region of the sky, scanning the galaxy with NIRCam for 167 hours and MIRI for 43 hours, requiring a total of nine days of valuable JWST time.
Fortunately, MIRI was perfectly aligned so that the researchers could view the galaxy clearly—any slight misalignment could have cost them this unexpected discovery.
JADES-GS-z14-0 is particularly striking because it is rich in oxygen. The exact timeline for early star formation remains uncertain, but two key events set the boundaries for when it could have begun. About 380,000 years after the Big Bang, recombination occurred, allowing hydrogen and helium atoms to form—essential elements for fueling the first stars.
The oldest known galaxy dates to 400 million years after the Big Bang, meaning that star formation must have been well underway by that point. The first stars emitted ultraviolet light, breaking down the early universe’s neutral hydrogen gas into hydrogen ions and free electrons. This process, called reionization, allowed light to travel freely through the cosmos, lifting the hydrogen fog that had previously blocked its path.
Oxygen as a Clue to Early Star Formation
In astronomical terms, any element heavier than helium is classified as a “metal.” These heavier elements appeared later, as they were forged through generations of stars forming and dying. The early universe contained only hydrogen, helium, and trace amounts of lithium.
Surprisingly, JADES-GS-z14-0 has an unexpectedly high oxygen content, suggesting it had been forming stars for at least 100 million years. These stars would have gone supernova, releasing oxygen into space, which then contributed to the next generation of star formation before the University of Arizona team discovered the galaxy.
“It’s a very complicated cycle to get as much oxygen as this galaxy has. So, it is genuinely mind-boggling,” senior author George Rieke said.
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Implications for Astronomy
“Imagine a grain of sand at the end of your arm. You see how large it is on the sky – that’s how large we looked at,” Helton said.
The discovery compresses the timeline between the Big Bang and galaxy formation, prompting scientists to reexamine existing galaxy formation models. JWST continues to push the boundaries of observation, revealing details from the universe’s earliest epochs and offering unprecedented insights into its evolution.
“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.”
The paper “Photometric Detection at 7.7 μm of a Galaxy Beyond Redshift 14 with JWST/MIRI” appeared on March 7, 2025, in Nature Astronomy.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.