In the early days of the solar system, these still-forming giant planets would duck, do a do-si-do, and throw one of their partners away from the sun’s gravitational grip. Things worked out, our planetary system is in its final configuration.
What triggered the planetary shuffling is currently unknown. Now, computer simulations show that, The young sun is evaporating its planet-forming disk of gas and dust This led to chaos in the orbits of giant planets, the researchers reported on April 28. nature.
Therefore, the four largest planets may have been in their final form within 10 million years of the birth of the solar system some 4.6 billion years ago. This is much faster than the 500 million years suggested by previous work.
Astrophysicist Nelson Ndugu, who studies planetary system formation at Northwestern University in Potchefstroom, South Africa, and Muni University in Arua, Uganda, says the planetary-shuffling mechanism the team discovered in computer simulations is very innovative. “It has huge potential.”
Extensive evidence, including observe Formation of extrasolar planetary systems (SN: July 2, 2018), has shown that in the early history of our solar system, something disturbed the orbits of giant planets, which scientists call giant planet instability (Serial Number: 5/25/05).
“The evidence for giant planet instability is very strong,” said planetary scientist Seth Jacobson of Michigan State University in East Lansing. “It explains a lot of the features of the outer solar system,” he said, like the vast number of solar systems rock object Beyond Neptune that makes up the Kuiper Belt (SN: December 31, 2009).
To figure out what caused this instability, Jacobson and colleagues ran computer simulations of thousands of ways the early solar system might have developed. It all starts with a young star and a planetary disk of gas and dust that forms around the star. The team then changed the disk parameters, such as its mass, density and evolution rate.
The simulations also included giant planets that were still forming — five of them, in fact.astronomer Think about the third ice giantwith the exception of Uranus and Neptune, were originally members of the solar system (SN: April 20, 2012). Jupiter and Saturn complete the final tally of these giant planets.
When the Sun officially becomes a star, the moment it begins to burn hydrogen in its core—about 4.6 billion years ago—its ultraviolet radiation hits the disk’s gas, ionizing it and heating it to tens of thousands Spend. “It’s a very well-documented process,” Jacobson said. As the gas heats up, it expands and begins to flow away from the star from the interior of the stellar disk.
“The disk spreads the gas from the inside out,” said Beibei Liu, an astrophysicist at Zhejiang University in Hangzhou, China. He and Jacobson collaborated with astronomer Sean Raymond of the Laboratory for Astrophysics in Bordeaux, France. a new study.
In the team’s simulations, as the interior of the disk dissolves, the region loses mass, so embedded, still-forming planets feel less gravity from the region, Jacobson said. But the planet still feels the same degree of pull from the outer region of the disk.This gravitational torque can trigger a rebound effect, as the team says: “Initially, planets migrate in, they arrive [inner] At the edge of this disk, they reverse their migration,” Liu said.
Because of Jupiter’s massive mass, it is barely affected. However, Saturn moved outward and into the region, which, in the simulation, hosts three ice giants. That region became crowded, Liu said, and close planetary interactions ensue. An ice giant was kicked out of the solar system entirely, and Uranus and Neptune moved a little further from the sun, “and they gradually formed orbits that were close to the configuration of our solar system,” Liu said.
In their computer simulations, the researchers found that planetary reshuffling almost always ensues as solar radiation vaporizes the disk. “We cannot avoid this instability,” Jacobson said.
Now that the researchers understand what might cause the solar system’s shuffle, the next step is to simulate how the evaporation of the disk affects other objects.
“We’re very concerned about giant planets because their orbits are the initial driving force,” Jacobson said. “But now, we have to do follow-up work to show how this triggering mechanism relates to small objects.”