James Webb telescope finds heavy elements in galaxies 13 billion light-years away

October 3, 2026 at 08:45 PM2 min

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The James Webb Space Telescope detected carbon, oxygen, and silicon in three galaxies whose light traveled more than 13 billion years to Earth. The findings, published in Nature Astronomy, show the early universe was less pristine than previously thought, with heavy elements present just 500 million years after the Big Bang.

Key Facts

The James Webb Space Telescope observed three galaxies whose light traveled more than 13 billion years to Earth.
The study was published in Nature Astronomy and led by Yongda Zhu of the University of Arizona in Tucson.
The observations show the universe at about 500 million years old, roughly 3 percent of its current age.
The spectra revealed absorption signatures of carbon, oxygen, and silicon in the intergalactic gas.
The measurements required nearly 30 hours of exposure time using JWST's infrared capabilities.

Early Universe Composition

Shortly after the Big Bang, the universe consisted almost exclusively of hydrogen and a small amount of helium. Heavier elements, collectively called metals in astronomy, formed later through nuclear fusion inside the first stars. When these extremely massive stars exploded as supernovae, they ejected newly formed elements such as carbon, oxygen, and silicon into surrounding space. This ongoing exchange of material between galaxies and their environment is known as the baryon cycle.

JWST Observations and Findings

Astronomers previously assumed that intergalactic gas in this early phase was largely pristine and original. The new JWST measurements suggest this assumption must be revised. The researchers used the three distant galaxies as background light sources, whose light passed through the surrounding gas on its way to Earth. Chemical elements absorb and emit light at characteristic wavelengths, leaving distinct absorption patterns in the spectra. These detailed measurements were possible only with JWST's infrared capabilities and an exposure time of nearly 30 hours. Zhu manually searched the spectra and identified the signatures of carbon, oxygen, and silicon.