A Test Particle Monte Carlo Investigation of the CH4 Torus around Saturn

Abstract

The issue of CH4 escape on Titan is still under debate, and a range of escape rates from 10^24 to 10^27 s^{-1} has been reported in previous studies. One effective way of solving the CH4 escape dilemma is to investigate the morphology of the CH4 torus around Saturn, which varies with both the total CH4 escape rate on Titan and the CH4 energy distribution near its exobase. Such a torus is modeled via a test particle Monte Carlo approach in this study for a variety of CH4 escaping scenarios characterized by different energy distributions near the exobase. The model calculations indicate that the extension of the CH4 torus depends critically on the population of the high-energy tail of the CH4 energy distribution. The model also predicts several distinctive cavities in CH4 density related to mean motion resonances between Titan and the torus particles.