A Possible Scenario of Configuring Saturn-Titan System
Abstract
Large moons orbiting around gas giants are thought to form in gaseous circumplanetary disks. In contrast to Jupiter that has four large satellites known as Galilean moons, Saturn has only one large moon, Titan. Forming only one satellite in a disk is known to be difficult and no mechanism has successfully explained the formation of a single-moon system. The orbits of moons formed in a circumplanetary disk vary over time due to the interaction with the disk gas. Therefore, the final configuration of the system is determined when the disk has dissipated. According to previous N-body simulations, systems tend to have multiple moons or lose all the moons if a simple power-low disk is assumed. We simulated the orbital evolution of Titan-mass moons in the final evolution stage of various circumplanetary disks. Since the direction and speed of the orbital migration depend on the properties of the disks, we modeled dissipating circumplanetary disks with taking the effect of opacity into account when we calculate the temperature structure. In our N-body simulations, we initially placed multiple satellites when we terminated the mass flow from the protoplanetary disk and let the circumplanetary disk to dissipate. We found that the radial slope of the temperature structure characterized by the dust opacity produces a patch of orbits where the Titan-mass moons resist inward migration with a certain range of the viscosity. The patch assists satellites initially located in the outer orbits to remain in the disk, while those in the inner orbits falls onto the planet. We demonstrated for the first time that single-large-moon systems can form around giant planets. Our results suggest satellite formation was less-efficient in the outer radii of circumplanetary disks.
- Publication:
-
43rd COSPAR Scientific Assembly. Held 28 January - 4 February
- Pub Date:
- January 2021
- Bibcode:
- 2021cosp...43E.145F