31st Annual Meeting of the DPS, October 1999
Session 15. Edgeworth-Kuiper Belt Posters
Poster Group I, Monday-Wednesday, October 11, 1999, , Kursaal Center

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[15.01] Close Approaches of the trans--Neptunian Objects to Pluto Left Observable Signatures on Their Orbital Distribution

F. Roig, D. Nesvorny, S. Ferraz-Mello (IAG/USP)

It is shown that in addition to four outer planets (Jupiter to Neptune) also Pluto should be taken into account in studies of the orbital dynamics in the trans--Neptunian region. Pluto effect is particularly large on the orbits in the 2:3 Neptune mean motion resonance. The trajectories found stable over the age of the solar system when only the gravitational effect of four outer planets is considered are often destabilized there in the effect of close Pluto approaches. We estimate that many dynamically primordial bodies moving initially with low to moderate amplitudes in the 2:3 Neptune resonance (semimajor axis 39.45 AU) have been removed from their respective, otherwise stable locations, when their resonant amplitudes increased in the course of close encounters with Pluto. At large libration amplitude the orbits became exposed to chaotic changes and objects were ejected from the 2:3 resonance to Neptune--crossing trajectories. The process of the resonant amplitude excitation was especially efficient for the orbits with moderate and large inclinations (i>8 deg), where more than 50% of the population has been removed on 4\times109 years. We estimate that the remaining part of the primordial resonant population at these inclinations should have had its resonant amplitude excited to about 80 degrees. The effect of Pluto on low--inclination orbits is smaller. We have examined the distribution of 33 objects observed on the 2:3 resonant orbits (Plutinos) and found, that there could actually exist indications of the above mechanism. The resonant amplitudes of Plutinos are unusually high for 0.15This research was sponsored by F.A.P.E.S.P.

The author(s) of this abstract have provided an email address for comments about the abstract: froig@iagusp.usp.br

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