Physics of Tidal Disruption of Big Objects at the Close Encounter to Saturn

International audienceThe origin of Saturn's main rings is still debated. According to the "Nice model" of Late Heavy Bombardment, planets could experience significant amount of close encounters with bodies scattered from primordial Kuiper belt that surrounded the giant planets. Such primordial belt could have been significantly massive and may have contained a larger number of big objects than currently observed in the Kuiper Belt. In this work, we revisit the physical processes of tidal disruption of such big object passing inside the Saturn's Roche limit and discuss the possibility of the mass implantation around Saturn as a result of the tidal disruption. [Charnoz et al. 2009. Icarus 199, 413-428] utilized an analytical formula that is derived from simply assuming uniform distribution of energy within a body [Dones 1991. Icarus 92, 194-203] to obtain masses that are captured onto bound orbits around planet after close encounter. However, the physical processes of tidal disruption remained unclear, and thus we might need to re-assess the captured mass. In this work, we perform SPH simulations of close encounters of homogeneous and differentiated bodies around Saturn in order to investigate how such objects could be tidally destructed and how much mass could be captured around Saturn as a result of the destruction. We find that our numerical results are not always consistent with Dones' (1991) formula that, in general, significantly overestimates or underestimates the captured mass as the pericenter distance of the passing object becomes larger, depending on the mass of objects. Effects of rotation and self-gravity within the body will be also investigated. We show that there is a wide range of outcomes for tidal disruption and that the implantation of rings is possible