Jupiter's anomalous size and location in our solar system have astonished researchers for years, as they do not fit our understanding of planetary formation. Now, astronomers believe they've figured out how the gas giant got into its curious position.
According to current models, huge planets form on the outer edges of a system, migrate inwards and end very close to their star. Not Jupiter, however: a giant planet more than twice as massive as the rest of the solar system's planets, but it circled quite a bit.
The new research seems to have demystified Jupiter's story. According to computer simulations, the gas giant four times farther out of its present location, directly in Uranus' current orbit, slowly retreated over 700,000 years.
"This is the first time we have it Proof that Jupiter has formed far from the Sun and then moved to its current orbit," said astronomer Simona Pirani of Lund University in Sweden.
The research was based on asteroids, the so-called Trojans. These divide the Jupiter orbit. a group of Trojans circulates in front of Jupiter, and the other tracks behind them in curved regions that focus on the planet's Lagrange points.
But there is a riddle. The group before Jupiter contains about 50 percent more asteroids than the wake group.
"Asymmetry has always been a mystery in the solar system," said Lund University astronomer Anders Johansen.
The team conducted simulations of the Jupiter formation to find out what could have caused such a strange imbalance.
They tested different timeframes and even a migration pattern and found out that the scenario led to the Trojan populations. Today occurs when Jupiter began planetary seed about 4.5 billion years ago, an icy asteroid of about 18 billion astronomical units from the sun.
Within two to three million years, it would have begun to wander into its present position of 5.2 astronomical units. This took about 700,000 years.
As the journey began to approach the sun, carried away by the gravity of the gases remaining in the solar system, the baby planet gravitationally picked up the Trojans, more of them taking the lead group than the trailing group.
This happened before the planetesimal had increased its gas; At that time, the rock that collapsed to form the core of the planet still formed, so it is likely that the core of Jupiter is made up of rocks similar to the ones in the Trojans.
Where Jupiter emerged was a problem that annoyed planet scientists for a long time, as it appears that gas giants could not form near a star. The intense gravity, the stellar radiation (including heat) and the strong stellar wind in the vicinity would prevent the gas from staying together long enough to form a planet.
However, this contradicts earlier research that relied on the formation of nearby Jupiter. The sun, followed by churn, also provides a solution – to align Jupiter with what we understand based on observations from other planetary systems.
And if the simulations of the team are correct, the asteroids could be a useful source to find out previously unknown information about the gas giant.
"We can learn a lot about Jupiter's core and education by studying the Trojans," said Johansen.
NASA plans to launch a probe called Lucy Study it in October 2021, so we do not have to wait long to find out.
The research was accepted in Astronomy & Astrophysics and can be read on arXiv.