Before there were planets around the Sun, there were rings.
The way material orbiting Saturn is flattened into a tight, clean disk by centrifugal forces is what happened with the Sun in the early days of the Solar System—and the way those rings were composed, it Tells how the Earth grew out of those rings. Not in manageable size and the so-called “Super-Earth”.
Super-Earths are rocky terrestrial worlds around other stars that are much larger than our own Earth, the largest rocky planets in our solar system, and that make up about 30% of the rocky exoplanets ever discovered.
We avoided that fate, thanks to “pressure bumps” in those early solar rings, according to a new study published in the journal Nature Astronomy.
An international team of researchers from Rice University, the University of Bordeaux, the Southwest Research Institute in Boulder, Colorado, and the Max Planck Institute for Astronomy in Heidelberg, Germany, ran hundreds of supercomputer simulations to reconstruct the formation of the Solar System.
What they found was that three bands of high pressure in the early solar accretion disk could account for everything from the composition of the asteroid belt between Mars and Jupiter and the formation of the Kuiper Belt beyond Neptune, but the nearly circular orbits of the four as well. Inner planets, their composition and their different sizes.
“Our model shows that pressure bumps can concentrate dust, and that moving pressure bumps can act as planetary factories,” Rice University astronomer Andre Izidoro, who led the study, said in a statement. Various phases, from tiny millimeter-sized grains to planets and then planets.
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“We propose that pressure constraints produced disconnected reservoirs of disk material in the inner and outer solar systems and controlled how much material was available for developing planets in the inner solar system.”
Had the disk been uniform, or “smooth,” in its composition, the Solar System would have a very different makeup than it is today.
“In a smooth disk, all solid particles — dust grains or boulders — must be pulled inward very quickly and lost in the star,” said Andrea Isella, an associate professor of physics and astronomy at Rice and a co-author of the study. he said. “One needs something to stop them to give them time to evolve as planets.”
At these pressure bumps, the gas condenses and the gas particles move faster, which in turn helps slow the flow of heavy solid material, such as dust and rock, from which it begins to accumulate in the planets.
Researchers believe the key is the accelerated formation of the second, middle ring in the solar disk. When they ran the simulation with a late-forming second ring of material, it allowed for more solid material in the inner solar system. This led to the formation of Super-Earth, but a rapidly forming second ring led to a solar system like ours.
“By the time the pressure collisions occurred in those cases, a lot of mass had already invaded the inner system and was available to form a super-Earth,” Izidoro said. “So the time when this mid-pressure collision could be an important aspect of the Solar System.”
Analysis: Finding out how we got here will help us find alien life there, if it exists
Super-Earths are not necessarily Earth-like, just larger, as the mathematics and physics of the universe tend to lead to large rocky bodies that have significantly greater gravity because their radii are larger.
If the Earth were ten times as large – assuming the same density as our own Earth, which if its composition were proportionally the same as it is now – then Earth’s gravity would also be ten times greater.
So, if you weigh 100 kilograms on Earth, you’ll weigh 1,000 kilograms on the Super-Earth, and our muscles and skeletons need to be more, more strong, to support that extra weight. It would be like squeezing the entire mass of a fully grown bull into a human frame.
Needless to say, this would fundamentally change the way life evolved on Earth, if it could develop at all. The increase in gravity also has a significant effect on whether a protective magnetic field can develop. Without one, UV radiation would have killed off most life on the planet and the solar winds would have stripped away much of our atmosphere (which we suspect happened on Mars).
Knowing the conditions that would allow life to form as we know it would then help us figure out which exoplanets are more likely to have life. And with the limited amount of resources we have for exploration, the more we can narrow down the list of candidate planets, the better our chances of success.
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