09:15 〜 09:30
[AOS14-02] Simulation of proto-Uranian disk formation by a giant impact: Equation of state and scheme of SPH method dependence
キーワード：SPH法、天王星
Present-day Uranus, its major satellites and rings have an inclination of roughly 98 degrees. One hypothesis to explain this feature is the giant impact theory. This theory proposes that Uranus' rotation axis was tilted by a giant impact, and the satellites were formed from the disk generated by the impact. Numerical fluid simulations of giant impacts have been performed using the Smoothed Particle Hydrodynamics (SPH) method (e.g., Slattery et al. 1992; Kegerreis et al. 2018; Reinhardt et al. 2020). These simulations predicted a disk that is generally heavy and compact, with a small proportion of rocky components. This was seen as inconsistent with the current Uranus satellite system, but the work of Ida et al. (2020) showed that the disc mass and size discrepancy is resolved by the evolution of the disk up to ice recondensation. However, the amount of rock in the disk varies from simulation to simulation, and the problem of the rocky composition of Uranus' moons relative to Uranus has not been fully resolved.
One possible reason for this difference is the difference in the equation of state. In the simulation of a giant impact of lunar formation, the Density Independence SPH method, which was improved to solve the difficulty of handling the SPH method on a discontinuity surface (Saitoh & Makino, 2013; Hosono et al. ), the properties of the disks formed are different. Therefore, we performed numerical simulations of giant impacts in the Uranus system using the three equations of state in both the standard SPH and DISPH methods to investigate the effect of the different equations of state and schemes on the properties of the formed disks. The results show that rock-rich disks are formed when calculations are performed with DISPH using ANEOS for rocks and SESAME EOS for ice. The results of these calculations and an analysis of the causes are presented.
One possible reason for this difference is the difference in the equation of state. In the simulation of a giant impact of lunar formation, the Density Independence SPH method, which was improved to solve the difficulty of handling the SPH method on a discontinuity surface (Saitoh & Makino, 2013; Hosono et al. ), the properties of the disks formed are different. Therefore, we performed numerical simulations of giant impacts in the Uranus system using the three equations of state in both the standard SPH and DISPH methods to investigate the effect of the different equations of state and schemes on the properties of the formed disks. The results show that rock-rich disks are formed when calculations are performed with DISPH using ANEOS for rocks and SESAME EOS for ice. The results of these calculations and an analysis of the causes are presented.