Mean motion resonances in the transneptunian region part II: The 1:2, 3:4, and weaker resonances

The stability of orbits in the transneptunian region is numerically computed. It is found that, in analogy to the asteroid belt, there exist many chaotic layers associated with thin mean-motion resonances. These are either moderate- and high-order resonances with Neptune or three-body resonances with Neptune and Uranus. The orbital eccentricity chaotically increases at the thin resonances, allowing some Kuiper Belt objects to be slowly transferred to Neptune-crossing orbits. The stability of two large mean-motion resonances with Neptune, the 1:2 and 3:4, is systematically explored. It is shown that orbits in both resonances, with small resonant amplitudes are stable over the age of the Solar System. The possible role of collisions and dynamical scattering in clearing the resonances is discussed. It is inferred from orbital angles of 1997 SZ10 and 1996 TR66 that these bodies are most probably on stable tadpole orbits in the 1 :2 Neptune resonance. (C) 2001 Academic Press.