Plate Nº 63 · recorded October 10, 2026
Space & AstronomyReported finding
Early galaxies were already seeding the universe with heavy elements
JWST has detected oxygen, carbon, and silicon flowing out of three galaxies seen as they existed just 500 million years after the Big Bang—far earlier than astronomers expected.
By Marcus Bennett3 min read671 words
In brief
- Heavy-element signatures (oxygen, carbon, silicon) were detected in three galaxies dated to about 500 million years after the Big Bang, roughly 3% of the universe's current age.
- JWST logged nearly 30 hours of exposure to capture the faint spectra used in the analysis.
- The study was led by Yongda Zhu of the University of Arizona's Steward Observatory.
- It was published in Nature Astronomy in 2026 with DOI 10.1038/s41550-026-02988-2.
- Absorption lines were blueshifted, indicating the heavy elements were moving outward from the galaxies into intergalactic space.
Astronomers using NASA's James Webb Space Telescope have detected oxygen, carbon, and silicon escaping from three galaxies observed as they existed only 500 million years after the Big Bang—roughly 3% of the universe's current age. The finding, published in Nature Astronomy, suggests these infant galaxies had already begun polluting intergalactic space with heavy elements, far earlier than most models predicted.
Lead author Yongda Zhu, a postdoctoral researcher at the University of Arizona's Steward Observatory, summed it up: "We observed that heavy elements escaped from galaxies very, very early in cosmic time. Not only were the galaxies producing these elements, but they were also dispersing them, possibly seeding other galaxies."
What did astronomers expect to see?
Before this study, the prevailing view held that gas around the first galaxies should have stayed mostly pristine—hydrogen and helium left over from the Big Bang, with little contamination from heavier elements.
Heavy elements (anything beyond helium on the periodic table) form only inside stars. Inside stellar cores, nuclear fusion builds carbon, oxygen, and silicon. Stars later shed those elements through stellar winds or supernova explosions.
If heavy elements appear around galaxies only 500 million years after the Big Bang, the "pristine" picture no longer fits the data.
How did the team detect the elements?
The researchers used a clever trick. "We used the galaxies themselves as background light sources," Zhu said. "As light from the galaxies traveled toward Earth, it passed through surrounding gas, and we were able to look at the light's absorption patterns to detect specific elements."
The method unfolded in four steps:
- The team combed publicly available JWST spectra from hundreds of galaxies.
- They manually searched the data during one long night.
- They pinpointed three galaxies whose spectra showed absorption from carbon, oxygen, and silicon.
- The absorption lines were blueshifted, meaning the gas was moving toward Earth—away from the galaxies.
JWST's infrared sensitivity made the measurement possible. The team logged nearly 30 hours of exposure to gather enough light from these faint, distant sources. The telescope captured galaxies as they appeared more than 13 billion years ago, during a period astronomers call the Epoch of Reionization, when the first stars stripped electrons from hydrogen atoms and ended the cosmic "dark ages."
What is baryon cycling?
Baryon cycling describes how galaxies exchange matter with their surroundings. Material forged inside stars gets blown into space, mixes with surrounding gas, and eventually falls back into new galaxies. This recycling means galaxies are not isolated islands but parts of a connected ecosystem.
Zhu used a kitchen analogy: "Think of these elements, which originated from the galaxies' stars, as food dye dropped into a cup of water. The color begins to spread through the water, and, in a similar fashion, these heavy elements from early galaxies began to escape into space and 'enrich' their surroundings."
Why does this complicate the search for the first stars?
The discovery may explain a long-standing puzzle: astronomers have hunted for Population III stars for decades without success. Population III refers to the first stars in cosmic history, which formed from gas containing no contamination—before heavy elements existed.
If galaxies were already enriching their surroundings only 500 million years after the Big Bang, truly pristine gas (and the Population III stars that formed from it) may have vanished too quickly to observe.
Zhu offered another analogy: "If you start out with pure vanilla ice cream but start mixing in sprinkles soon after, it won't be long until you can no longer find any pristine, plain vanilla ice cream."
What are the limitations?
The team studied only three galaxies, and the chemical analysis grew out of one night's manual search through archival spectra. A larger statistical sample, combined with follow-up JWST observations, will help confirm how widespread early metal enrichment really was.
The study, "Early metal-enriched baryon cycling before the midpoint of cosmic reionization," appeared in Nature Astronomy in 2026. Its DOI is 10.1038/s41550-026-02988-2.
via Phys.org Space & Astronomy (Source)
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