Unbiased Inclination Distributions for Objects in the Kuiper Belt

TL;DR

This paper derives an unbiased method to analyze inclination distributions of Kuiper Belt objects, revealing distinct dynamical class characteristics and providing insights into Solar System evolution.

Contribution

It introduces a new bias removal procedure for inclination data and applies it to classify KBOs by their inclination distributions across different dynamical classes.

Findings

80% of KBOs are in high-inclination groups

Classical KBOs fit two-Gaussian inclination models

Centaurs have inclination peaks near 20 degrees

Abstract

Using data from the Deep Ecliptic Survey (DES), we investigate the inclination distributions of objects in the Kuiper Belt. We present a derivation for observational bias removal and use this procedure to generate unbiased inclination distributions for Kuiper Belt objects (KBOs) of different DES dynamical classes, with respect to the Kuiper Belt Plane. Consistent with previous results, we find that the inclination distribution for all DES KBOs is well fit by the sum of two Gaussians, or a Gaussian plus a generalized Lorentzian, multiplied by sin i. Approximately 80% of KBOs are in the high-inclination grouping. We find that Classical object inclinations are well fit by sin i multiplied by the sum of two Gaussians, with roughly even distribution between Gaussians of widths 2.0 -0.5/+0.6 degrees and 8.1 -2.1/+2.6 degrees. Objects in different resonances exhibit different inclination distributions. The inclinations of Scattered objects are best matched by sin i multiplied by a single Gaussian that is centered at 19.1 -3.6/+3.9 degrees with a width of 6.9 -2.7/+4.1 degrees. Centaur inclinations peak just below 20 degrees, with one exceptionally high-inclination object near 80 degrees. The currently observed inclination distribution of the Centaurs is not dissimilar to that of the Scattered Extended KBOs and Jupiter-family comets, but is significantly different from the Classical and Resonant KBOs. While the sample sizes of some dynamical classes are still small, these results should begin to serve as a critical diagnostic for models of Solar System evolution.