It is known that gas giants around other stars are often very close to their sun. According to accepted theory, these gas planets were formed far away and subsequently migrated to a path closer to the star.
Now, researchers from Lund University and other institutions have used advanced computer simulations to learn more about Jupiter's journey through our own solar system about 4.5 billion years ago. At that time, Jupiter was recently formed, like the other planets in the solar system. The planets were gradually built up by cosmic dust circling around our young sun on a disk of gas and particles. Jupiter was no bigger than our own planet.
The results show that Jupiter was formed four times longer from the sun than the current position would indicate.
"This is the first time we have evidence that Jupiter was forming a long way from the sun and then migrating to its current circuit. We found signs of migration in the Trojan asteroids that are close to Jupiter," Simona Pirani explains. , PhD student in astronomy at Lund University and principal author of the study. [1
"Asymmetry has always been a mystery in the solar system," says Anders Johansen, professor of astronomy at Lund University.
The research environment has previously been unable to explain why the two asteroid groups do not contain the same number of asteroids. However, Simona Pirani and Anders Johansen, together with other colleagues, have now identified the cause by restoring the events in Jupiter's formation and how the planet gradually withdrew into its Trojan asteroids.
Thanks to extensive computer simulations, scientists have calculated that the current asymmetry could only occur if Jupiter was formed four times further into the solar system and then migrated to its current position. During his journey to the sun, Jupiter's own gravity drew more trojans in front of it than behind it.
According to the calculations, Jupiter's migration lasted for about 700,000 years, for a period of approx. 2-3 million years after the celestial body started its life as an ice steroid far from the sun. The journey inward into the solar system followed a spiral course, where Jupiter continued to circle around the sun, albeit in an increasingly tight path. The reason behind the actual migration relates to gravity from the surrounding gases in the solar system.
The simulations show that the Trojan asteroids were pulled in as Jupiter was a young planet with no gas atmosphere, which means that these asteroids most likely consist of the building blocks corresponding to those that formed the Jupiter core. In 2021, NASA's space probe Lucy will be launched in orbit around six of Jupiter's Trojan asteroids to study them.
"We can learn a lot about Jupiter's core and formation from studying the Trojans," says Anders Johansen.
The authors of the study also suggest that the gas giant Saturn and the ice giants Uranus and Neptune could have migrated in the same way.
Materials from Lund University . Note: The content can be edited for style and length.