On a Possible Size/Color Relationship in the Kuiper Belt

TL;DR

This study investigates the relationship between size and color in Kuiper Belt Objects, finding that color distribution correlates more with object classification than size, challenging previous models based on magnitude.

Contribution

The paper introduces synthetic models of KBO colors based on size and classification, comparing them to observational data to evaluate their validity.

Findings

Color distribution varies with object classification.

H-Model is rejected by observational data.

Class-Model fits Hot population but not Cold population.

Abstract

Color measurements and albedo distributions introduce non-intuitive observational biases in size-color relationships among Kuiper Belt Objects (KBOs) that cannot be disentangled without a well characterized sample population with systematic photometry. Peixinho et al. report that the form of the KBO color distribution varies with absolute magnitude, H. However, Tegler et al. find that KBO color distributions are a property of object classification. We construct synthetic models of observed KBO colors based on two B-R color distribution scenarios: color distribution dependent on H magnitude (H-Model) and color distribution based on object classification (Class-Model). These synthetic B-R color distributions were modified to account for observational flux biases. We compare our synthetic B-R distributions to the observed 'Hot' and 'Cold' detected objects from the Canada-France Ecliptic Plane Survey and the Meudon Multicolor Survey. For both surveys, the Hot population color distribution rejects the H-Model, but is well described by the Class-Model. The Cold objects reject the H-Model, but the Class-Model (while not statistically rejected) also does not provide a compelling match for data. Although we formally reject models where the structure of the color distribution is a strong function of H magnitude, we also do not find that a simple dependence of color distribution on orbit classification is sufficient to describe the color distribution of classical KBOs.