摘要：The formation of Pluto’s small satellites—Styx, Nix, Keberos, and Hydra—remains a mystery. Their orbits are nearly circular and are near mean-motion resonances and nearly coplanar with Charon’s orbit.One scenario suggests that they all formed close to their current locations from a disk of debris that was ejected from the Charonforming impact before the tidal evolution of Charon. The validity of this scenario is tested by performing N-body simulations with the small satellites treated as test particles and Pluto–Charon evolving tidally from an initial orbit at a few Pluto radii with initial eccentricity eC=0 or 0.2. After tidal evolution, the free eccentricities efree of the test particles are extracted by applying fast Fourier transformation to the distance between the test particles and thecenter of mass of the system and compared with the current eccentricities of the four small satellites. The only surviving test particles with efree matching the eccentricities of the current satellites are those not affected by meanmotion resonances during the tidal evolution in a model with Pluto’s effective tidal dissipation function Q=100 and an initial eC=0.2 that is damped down rapidly. However, these test particles do not have any preference to be in or near 4:1, 5:1, and 6:1 resonances with Charon. An alternative scenario may be needed to explain theformation of Pluto’s small satellites.
关键词：celestial mechanics;Kuiper belt objects: individual (Pluto);planets and satellites: individual (Styx,Nix, Kerberos, Hydra)
