OSSOS. XIV. The Plane of the Kuiper Belt

Abstract

The orbits of solar system objects are subject to perturbations by other massive bodies and slowly precess about a forced (averaged) plane. Warps in the plane come from the effects of the total planetary system, so discrepancies from expectation can show the presence of any unseen planets. We investigate the orbital inclination distribution from 42.4 to 150 au with the nonresonant trans-Neptunian discoveries and the survey simulator of the Outer Solar System Origins Survey (OSSOS). We statistically determine local forced planes and the widths of the populations’ inclination distributions. Between the ν 18 (near 40.3 au) and the 2:1 (at 47.5 au), the derived forced plane and the expected forced plane (from secular perturbations due to the known planets) match very well. As in previous studies, we reject the ecliptic as the forced plane. We also reject the invariable plane inside of 44.4 au, beyond which the forced plane starts approaching the invariable plane. From 44.4 to 150 au the forced plane is consistent with the invariable plane, as expected based on the known planets. The dynamically cold Kuiper belt (between the ν 18 and the 2:1 resonance) is best fit with a free inclination width of only ≃1.°75, strongly limiting its past perturbation. The dynamically excited populations have broader inclination distributions: the hot Kuiper belt is ≃14° wide, and nonresonant orbits in the semimajor axis range beyond the 2:1 resonance out to 150 au have an inclination width of ≃17°. The OSSOS data do not strengthen claims of present additional Mars-mass planets within ∼100 au.