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C.B. Agnor (U.C. Santa Cruz), D.P. Hamilton (U. Maryland)
The recent observational discovery of satellites orbiting asteroids and Kuiper belt objectss has revealed a whole new constituency of solar system objects (see Merline et al. 2002 for a review). Binaries appear to be ubiquitous among the minor planets, representing ~6% of near-Earth asteroids (Margo et al. 2002), ~% of asteroids in the main belt (Merline et al. 2002), and ~5% of KBOs (Noll et al. 2003). Here we consider the possibility that Triton may have been captured during a gravitational encounter between Neptune and a binary composed of Triton and a third body.
Given the existence and prevalence of binaries, 3-body encounters between a binary pair and a third body become an inevitable and frequent occurrence in the dynamical evolution of the solar system. This type of encounter has been studied previously in the context of stellar clusters where binary-single star encounters represent an important process in the evolution of binary star populations (see e.g. Hills 1975, Heggie & Hut 1993). The possible outcomes of these encounters include physical collisions, hardening, softening or disrupting the binary, and exchange reactions in which one member of a binary is expelled and its place taken by the third body. In the context of solar system dynamics, the significance of 3-body encounters is only beginning to be examined and appreciated (Funato et al. 2004).
We will report on progress in our study of 3-body encounters between a planet and a binary and discuss the implications of this dynamical process for the origin and evolution of major and minor planet satellites. In particular we will address how exchange reactions during planet-binary encounters represent a new pathway for the capture of Triton and other irregular planetary satellites from initially heliocentric orbits.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.