The Origin and Evolution of Transneptunian Binaries: Excitation of Binary Orbit Eccentricity via the Kozai-Lidov Mechanism

This animation shows the evolution of the properties of binary planetesimals during a simulation of the outward migration of Neptune, as presented in the PhD thesis: "The Origin and Evolution of Transneptunian Binaries" by J. E. Robinson.

The figure axes indicate the binary semimajor axis and eccentricity, while the colour scheme denotes the binary orbit inclination. During the simulation binaries above a critical separation (denoted by the red vertical line) undergo oscillations in eccentricity which allow them to evolve onto non-circular orbits (above the horizontal red line). These objects are experiencing binary orbit Kozai-Lidov oscillations; only binaries with inclinations sensitive to Kozai (40 < i < 140 degrees) display this behaviour.