Standard models of galactic evolution indicated that the universe needed several billion years after the Big Bang to produce enough heavy elements for rocky planets. Vorobyov and co-author Daniel Whalen at the University of Portsmouth tested the accuracy of the time scale using computational models. Their team found evidence that raw planetary material formed far earlier.
The earliest stars, known as Population III stars, formed from primordial gas lacking heavy elements. Many of these stars grew large, burned fuel rapidly, and exploded as supernovae. One specific type, called a pair-instability supernova, releases exceptional energy, ejecting more than 100 times the sun’s mass in heavy elements during a single explosion.
Using computer simulations, the team modeled how debris from these explosions settled around newer, smaller stars. The models generated stars around 70% the mass of the sun surrounded by debris disks. These disks contained enough material to form planetary building blocks several times the mass of Earth at distances comparable to Earth’s orbit. The disks also contained abundant water.
In a University of Portsmouth press statement, Whalen noted that PhD student Chris Jessop ran the initial simulations. The team demonstrated that precursors to terrestrial planets could form around low-mass stars in supernova debris just 100 million years after the Big Bang.
Water serves as a key indicator in this process. Oxygen atoms form inside large stars and scatter into surrounding gas through supernova explosions. That oxygen later integrates into new planetary systems. Earlier research by Whalen’s group showed that Population III supernovae produced water even in low-metallicity gas 180 million years after the Big Bang.
Observational data supports the presence of early water. Astronomers have detected water in a massive galaxy billions of light-years away, marking the most distant water detection recorded in a star-forming galaxy. Researchers emphasize that detecting early water indicates the presence of raw materials rather than evidence of life.
The study relies on computer simulations rather than direct observations of physical planets from that era. Confirming when the first rocky worlds formed requires advanced telescopes capable of observing the early universe in greater detail.
Whalen noted that if conditions for planet formation emerged earlier than assumed, researchers must consider whether habitable worlds also formed earlier in cosmic history. That question remains open as astronomers continue to probe the early universe.
Source: Vorobyov, E.I., Whalen, D.J., Latif, M.A. et al. “Planet Formation at Cosmic Dawn: Planetesimals in H2O-Rich Disks Around Low-Mass Stars.” The Astrophysical Journal Letters (2026).