Evolution of primordial Kuiper belt binaries through a giant planet instability

ABSTRACT The non-resonant Kuiper belt objects between the 3:2 and 2:1 Neptunian mean motion resonances can be largely divided a cold classical (CCB) hot (HCB). A notable difference these two subpopulations is prevalence of widely spaced, equal-mass binaries in CCB, much smaller but non-zero number HCB. primary reason for this binary rate remains unclear. Here using N-body simulations we examine whether close encounters with giant planets during an early outer Solar system instability may have disrupted primordial that existed within before they attained HCB orbits. We find such are very effective at disrupting down to separations ∼ 1% their Hill radius' (as measured modern belt), potentially explaining paucity equal mass Moreover, widest observed quite unlikely survive planetary encounters, same widen small subset tighter give rise population wide seen today's