Mystery solved behind birth of Saturn’s rings | Kobe University
http://www.kobe-u.ac.jp/en/NEWS/research/2016_10_31_01.html
A team of researchers has presented a new model for the origin of Saturn’s rings based on results of computer simulations. The results of the simulations are also applicable to rings
of other giant planets and explain the compositional differences between the rings of Saturn and Uranus. The findings were published on October 6 in the online version of Icarus.
The lead author of the paper is HYODO Ryuki (Kobe University, Graduate School of Science), and co-authors are Professor Sébastien Charnoz (Institute de Physique du Globe/Université Paris
Diderot), Professor OHTSUKI Keiji (Kobe University, Graduate School of Science), and Project Associate Professor GENDA Hidenori (Earth-Life Science Institute, Tokyo Institute of Technology).
The present study focused on the period called the Late Heavy Bombardment that is believed to have occurred 4 billion years ago in our solar system, when the giant planets underwent orbital
migration. It is thought that several thousand Pluto-sized (one fifth of Earth’s size) objects from the Kuiper belt existed in the outer solar system beyond Neptune. First the researchers
calculated the probability that these large objects passed close enough to the giant planets to be destroyed by their tidal force during the Late Heavy Bombardment. Results showed that
Saturn, Uranus and Neptune experienced close encounters with these large celestial objects multiple times.
Next the group used computer simulations to investigate disruption of these Kuiper belt objects by tidal force when they passed the vicinity of the giant planets (see Figure 2a). The results
of the simulations varied depending on the initial conditions, such as the rotation of the passing objects and their minimum approach distance to the planet. However they discovered that in
many cases fragments comprising 0.1-10% of the initial mass of the passing objects were captured into orbits around the planet (see Figures 2a, b). The combined mass of these captured
fragments was found to be sufficient to explain the mass of the current rings around Saturn and Uranus. In other words, these planetary rings were formed when sufficiently large objects
passed very close to giants and were destroyed.