Astronomers have detected carbon in a galaxy observed just 350 m years after the Big Bang, in observations that raise the possibility that the conditions for life were present almost from the beginning of time.
The observations, made by the James Webb Space Telescope suggests that large amounts of carbon were released when the first generation of stars exploded into supernovae. Carbon is known to have seeded the first planets and is a building block for life as we know it, but was previously thought to have emerged much later in cosmic history.
“This is the earliest detection of an element heavier than hydrogen ever obtained,” said Prof Roberto Maiolino, an astronomer at the University of Cambridge and a co-author of the findings. “This is a massive discovery.”
“Finding a large amount of carbon in such a distant galaxy implies that life could have possibly originated very early in the universe, really close to cosmic dawn.”
The very early universe consisted almost entirely of hydrogen, helium and small amounts of lithium. Every other element – including those that formed Earth and humans – was formed in stars and released during supernovae, when stars explode at the end of their lives. With each new generation of stars, the universe was enriched with increasingly heavier elements until rocky planets formed and life became a possibility.
Carbon is a fundamental element in this process, as it can clump together into dust grains in a swirling disk around stars, and eventually snowball into the earliest planets. Carbon enrichment was previously thought to have occurred about 1 billion years after the Big Bang.
The latest research dates the earliest carbon fingerprint to just 350m years, suggesting that carbon was released in large quantities in the supernovae of the very first generation of stars in the universe. This does not change estimates for when life began on Earth, about 3.7 billion years ago, but suggests that some of the criteria for life originating elsewhere in the universe were present much earlier than expected.
“The very first stars are the holy grail of chemical evolution, as they are made only of primordial elements, and they behave very differently from modern stars,” says Dr Francesco D’Eugenio, an astrophysicist at the Kavli Institute for Cosmology at Cambridge and the lead author of the findings. “By studying how and when the first metals formed inside stars, we can set a time frame for the earliest steps on the path that led to the formation of life.”
The galaxy, which is the third most distant ever observed, is small and compact – about 100,000 times smaller than the Milky Way.
“It’s just an embryo of a galaxy when we observe it, but it could develop into something quite large, about the size of the Milky Way,” D’Eugenio said. “But for such a young galaxy, it’s pretty massive.”
An analysis of the spectrum of light coming from the galaxy gave a confident detection of carbon and tentative detections of oxygen and neon. “From carbon to DNA is a big journey, but it shows that those key elements are already there in principle,” Maiolino said.
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Dr Rafael Alves Batista, an astrophysicist at Sorbonne University, Paris, who was not involved in the latest findings, said: “The result is a big leap forward and is something we did not know before.”
However, he said it was not possible to extrapolate from the detection of carbon to the likelihood of life emerging. “It’s not a leap I would make,” he said. “Most of these [early] stars are too massive so they die too quickly. Even if there are planets, I am not very optimistic that they will have the conditions for life. The findings are very interesting, but I don’t think they are sufficient to settle anything.”
The findings are expected to be published in the journal Astronomy & Astrophysics.
