The building blocks of rocky planets may have formed just 100 million years after the Big Bang, according to new research from the University of Portsmouth. The discovery suggests that planet formation could have begun remarkably early—before the first galaxies had fully developed.
Scientists have traditionally believed that planets formed much later, after the universe had existed for billions of years. However, the new study indicates that the essential ingredients for rocky planets may have emerged during the universe’s earliest stages.
How the first stars supplied the ingredients for planets
Some of the universe’s first stars, known as Population III stars, were extremely massive. At the end of their short lives, these stars exploded in powerful supernovae, releasing elements such as carbon, oxygen, and iron into the surrounding gas.
These explosions, known as “Pop III supernovae,” provided the universe’s first major supply of heavy elements—the raw materials needed to form planets and, ultimately, the chemical ingredients associated with life.
Dr Daniel Whalen, from the Institute of Cosmology and Gravity at the University of Portsmouth, said: “Our new paper, in which PhD student Chris Jessop ran the first part of the simulation chain, shows that precursors of terrestrial planets could form around low-mass, long-lived stars in the remains of the first cosmic explosion 100 million years after the Big Bang.”
“To put this into perspective, the universe is about 13.8 billion years old, so this is an incredibly early stage in the history of the universe.”
Powerful supernovae may create planet-forming disks
A particularly energetic type of Pop III supernova can eject more than 100 times the mass of the Sun in heavy elements during a single explosion.
This material can significantly increase the concentration of heavy elements in nearby clouds of gas. As gravity draws these enriched clouds together, they can form rotating disks around young stars. These planet-forming disks resemble the structures that eventually produced the planets in our own Solar System.
Dr Whalen added: “In computer simulations of the early universe, we found one such disk around a young star that weighed about 70 percent as much as the Sun. Within that disk, enough solid material accumulated to create the building blocks of several Earth masses worth of planets at about the same distance from the star as the Earth and the Sun.”
Water may have been available in the early universe
The simulations revealed another surprising feature: the planet-forming disk also contained a significant amount of water.
“Most surprisingly, this disk also contained significant amounts of water, an amount only a fraction of what was available when our solar system formed. This means that planets that formed there could potentially receive water in a similar way to Earth. Earth is thought to have gotten much of its water from material left over during the planet-forming process.”
“Our findings suggest that the conditions for planet formation may have existed much earlier than previously thought. If this is the case, it raises the interesting question that potentially habitable worlds may also have emerged much earlier in the history of the universe.”
The research suggests that rocky planets—and possibly worlds containing some of the ingredients linked to habitability—could have become possible far earlier in cosmic history than scientists previously expected.
The study is published in Astrophysics Letters Journal.
Source: www.sciencedaily.com