The building blocks of rocky planets could have started forming just 100 million years after the Big Bang - long before the first galaxies even existed, according to new research from the University of Portsmouth.
Scientists had previously assumed that planet formation was a slow process, only really getting going several billion years into the Universe's history, but a new study has found it happened far earlier than anyone had previously thought.
Some of the very first stars in the Universe were enormous and ended their lives in powerful explosions. These explosions scattered huge amounts of the chemical elements needed to build planets, such as carbon, oxygen and iron, into the surrounding gas.
These explosions, known as ‘Pop III supernovae’, were the Universe’s first factories for the elements needed to build planets and, ultimately, life.
Dr Daniel Whalen , from the University of Portsmouth’s Institute of Cosmology and Gravitation , said: “Our new paper, in which my PhD student Chris Jessop ran the first part of the simulation chain, shows that the precursors of terrestrial planets can form around low-mass, long-lived stars in the debris of the first cosmic explosions 100 million years after the Big Bang.
“To put this into perspective, the Universe is about 13.8 billion years old, so this is remarkably early in cosmic history.”
A particular type of Pop III supernova - called a pair-instability supernova - is so powerful that it can blast out more than 100 times the mass of the Sun's worth of heavy elements in a single explosion.
This material can enrich nearby clouds of gas to surprisingly high concentrations of heavy elements. Those enriched clouds can then collapse under gravity and form a swirling disc of material around a young star, much like the disc from which our own Solar System formed.
Dr Whalen added: “In our computer simulations of the early Universe, we found one such disc around a young star about 70 per cent as massive as the Sun. Within that disc, enough solid material accumulated to create several Earth-masses' worth of planetary building blocks at roughly the same distance from the star as Earth is from the Sun.
“Most surprisingly, the disc also contained substantial amounts of water, only a few times less than what was available when our own Solar System formed. This means that any planets forming there could potentially have received water in a similar way to Earth, which is thought to have gained much of its water from material left over during the planet-building process.
“Our findings suggest that the conditions for planet formation may have existed much earlier than previously thought. If that's the case, it raises an intriguing question: could potentially habitable worlds have appeared far earlier in the Universe's history as well?”
The paper is published in The Astrophysical Letters Journal .
The Astrophysical Journal Letters
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