Researchers have dated Jupiter's birth to 1.8 million years after the beginning of the solar system by simulating the behavior of tiny particles preserved until today.
Four and a half billion years ago, Jupiter rapidly grew to its enormous size. Its powerful gravitational pull altered the orbits of small, rocky, icy bodies similar to modern asteroids and comets, called planetesimals. This caused them to collide with each other at such high speeds that the rocks and dust they contained melted upon impact, creating floating droplets of molten rock, or chondrules, preserved in today's meteorites.
Now, researchers from Nagoya University (Japan) and the Italian National Institute for Astrophysics (INAF) have determined for the first time how these droplets formed and have precisely dated Jupiter's formation based on their findings.
Their study, published in Scientific Reports, shows how the characteristics of chondrules, particularly their size and the rate at which they cooled in space, are determined by the water contained in the impacting planetesimals. This explains what we observe in meteorite samples and demonstrates that chondrules formed as a result of planet formation.
Chondrules, tiny spheres about 0.1 to 2 millimeters across, were incorporated into asteroids during the formation of the solar system . Billions of years later, fragments of these asteroids broke off and fell to Earth as meteorites. How chondrules acquired their round shape has intrigued scientists for decades.
"When the planetesimals collided with each other, the water instantly vaporized into expanding steam. This acted like small explosions and disintegrated the molten silicate rock into the tiny droplets we see in meteorites today," explained co-lead author Professor Sin-iti Sirono of Nagoya University's Earth and Environmental Sciences
"Previous formation theories could not explain the characteristics of chondrules without requiring very specific conditions, whereas this model requires conditions that occurred naturally in the early solar system when Jupiter was born."
HIGH-SPEED COLLISIONS
Researchers developed computer simulations of Jupiter's growth and traced how its gravity caused high-speed collisions between rocky, water-rich planetesimals in the early solar system.
“We compared the characteristics and abundance of simulated chondrules with meteorite data and found that the model spontaneously generated realistic chondrules. The model also shows that chondrule production coincides with Jupiter’s intense accretion of nebular gas to reach its enormous size. Since meteorite data indicate that the peak of chondrule formation occurred 1.8 million years after the beginning of the solar system, this is also the time of Jupiter’s birth,” said Dr. Diego Turrini, co-lead author and senior researcher at the Italian National Institute for Astrophysics (INAF).
This study provides a clearer view of how our solar system formed. However, according to the authors, the chondrule production initiated by Jupiter's formation is too brief to explain why we find chondrules of such different ages in meteorites. The most likely explanation is that other giant planets like Saturn also triggered chondrule formation at birth.
By studying chondrules of different ages, scientists can trace the birth order of the planets and understand how our solar system developed over time.
The research also suggests that these violent planet formation processes can occur around other stars and offers insights into how other planetary systems developed.
