Chaos and the Formation of Binary objects in the Kuiper-belt
Our calculations suggest that binaries are produced through the following chain of events. Initially, long-lived quasi-bound binaries form by two bodies getting entangled in thin layers of dynamical chaos produced by solar tides within the Hill sphere (i.e., chaos-assisted capture). Next, energy transfer through gravitational scattering with a low-mass intruder elbows the binary into a nearby non-chaotic (stable) zone of phase space. Finally, the binary hardens (loses energy) through a series of relatively gentle gravitational scattering encounters with further, low-mass, intruders. This produces binary orbits that are well fitted by Kepler ellipses. Dynamically, the overall process is strongly favoured if the original quasi-bound binary contains comparable masses.
Unexpectedly, chaos plays a twin role in the stabilization and destabilization of nascent binaries; it provides a mechanism for the formation of transient binaries but selectively destabilizes binaries containing partners having very unequal masses. This suggests that the observed preponderance of roughly equal-mass ratio binaries is a real effect and not simply an artefact of an observational bias for widely separated, comparably bright objects. Nevertheless, we predict that a sizeable population of very unequal-mass Kuiper-belt binaries is probably awaiting discovery.
Extensions of this mechanism to other problems of interest in the outer Solar System, as well as problems in atomic and molecular physics will be briefly discussed.