Astronomers have discovered carbon in a galaxy seen just 350 million years after the Big Bang, in observations that raise the possibility that conditions for life were present almost from the beginning of time.
The observations, made by the James Webb Space Telescope, suggest that huge amounts of carbon were released when the first generation of stars exploded in supernovae. Carbon is known to have spawned the first planets and is a building block for life as we know it, but it was previously thought to have emerged much later in cosmic history.
“This is the earliest detection ever of an element heavier than hydrogen,” said Prof. Roberto Maiolino, an astronomer at the University of Cambridge and co-author of the findings. “It’s a huge discovery.”
“The discovery of a large amount of carbon in such a distant galaxy implies that life could have originated very early in the universe, very close to the 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 supernovas, when stars explode at the end of their lives. With each new generation of stars, the universe was enriched with heavier and heavier elements until rocky planets emerged and life became possible.
Carbon is a fundamental element in this process, because it can clump into grains of dust in a swirling disk around stars, eventually snowballing into the earliest planets. It was previously thought that carbon enrichment occurred about 1 billion years after the Big Bang.
The latest research dates the earliest carbon fingerprint to just 350 million years, suggesting that carbon was released in large quantities by the supernovae of the universe’s very first generation of stars. This doesn’t change estimates of when life began on Earth, about 3.7 billion years ago, but suggests that some criteria for the origins of life elsewhere in the universe were in place much earlier than expected.
“The very first stars are the holy grail of chemical evolution, because they consist exclusively of primordial elements and behave very differently from modern stars,” says Dr Francesco D’Eugenio, an astrophysicist at the Kavli Institute of Cosmology in Cambridge and to the lead author of the findings. “By studying how and when the first metals formed in stars, we can pinpoint a time frame for the first steps on the path that led to the formation of life.”
The galaxy, the fifth most distant galaxy ever observed, is small and compact: about 100,000 times smaller than the Milky Way. “If we observe it, it is just an embryo of a galaxy, but it could grow into something very big, about the size of the Milky Way,” says D’Eugenio. “But for such a young galaxy, it is quite massive.”
An analysis of the spectrum of light emanating from the Milky Way yielded reliable detections of carbon and tentative detections of oxygen and neon. “From carbon to DNA is a huge journey, but this shows that these key elements are in principle already present,” says Maiolino.
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Dr. Rafael Alves Batista, an astrophysicist at Sorbonne University in Paris, who was not involved in the latest findings, said: “The result is a huge leap forward and is something we didn’t know before.”
However, he said it was not possible to extrapolate from the detection of carbon the likelihood of life arising. “That’s not a jump I would make,” he said. “Most of these [early] Stars are too heavy and therefore die too quickly. Even if there are planets, I’m not very optimistic that they would have the conditions for life. The findings are very interesting, but I don’t think they are enough to solve anything.”
The findings will be published in the journal Astronomy & Astrophysics.