[P-PS03] 太陽系小天体：太陽系進化における最新成果と今後の展望

[PPS03-P20] Conditions for the long term stability of Pluto's azimuthal and latitudinal perihelion librations

*伊藤 孝士^1,3、Malhotra Renu² (1.自然科学研究機構国立天文台、2.アリゾナ大学月惑星科学科、3.千葉工業大学惑星探査研究センター)

キーワード：冥王星、共鳴、太陽系力学、外縁天体

Many of the unusual properties of the dwarf planet Pluto's orbit are widely accepted as evidence for the orbital migration of the giant planets in early solar system history. However, some properties remain an enigma. Pluto's long term orbital stability is supported by two special properties of its orbit that limit the location of its perihelion in azimuth and in latitude. We revisit Pluto's orbital dynamics with a view to elucidating the individual and collective gravitational effects of the giant planets on its perihelion location. In this presentation we demonstrate with numerical experiments that, while the resonant perturbations from Neptune account for the azimuthal constraint on Pluto's perihelion location, the long term and steady persistence of the latitudinal constraint is possible only in a narrow range of additional secular forcing which arises fortuitously from the particular orbital architecture of the other giant planets. Our numerical investigations also find that Jupiter has a largely stabilizing influence whereas Uranus has a largely destabilizing influence on Pluto's orbit.