# The bimodal color distribution of small Kuiper Belt objects

## TL;DR

This study reveals a strong bimodal color distribution among small Kuiper Belt objects, with similar magnitude distributions across color subpopulations, supporting theories on their origins and relationships with Centaurs and Trojans.

## Contribution

First detailed analysis of magnitude distributions for color-defined subpopulations of small KBOs, confirming their similarity and linking to Centaurs and Trojans.

## Key findings

- Bimodal g-i color distribution in small KBOs.
- Color subpopulations have similar magnitude distributions.
- KBO color bimodality is linked to Centaurs and Trojans.

## Abstract

We conducted a two-night photometric survey of small Kuiper Belt objects (KBOs) near opposition using the wide-field Hyper Suprime-Cam instrument on the 8.2 m Subaru Telescope. The survey covered about 90 deg^2 of sky, with each field imaged in the g and i bands. We detected 356 KBOs, ranging in absolute magnitude from 6.5 to 10.4. Filtering for high-inclination objects within the hot KBO population, we show that the g-i color distribution is strongly bimodal, indicative of two color classes - the red and very red subpopulations. After categorizing objects into the two subpopulations by color, we present the first dedicated analysis of the magnitude distributions of the individual color subpopulations and demonstrate that the two distributions are roughly identical in shape throughout the entire size range covered by our survey. Comparing the color distribution of small hot KBOs with that of Centaurs, we find that they have similar bimodal shapes, thereby providing strong confirmation of previous explanations for the attested bimodality of Centaurs. We also show that the magnitude distributions of the two KBO color subpopulations and the two color subpopulations observed in the Jupiter Trojans are statistically indistinguishable. Finally, we discuss a hypothesis describing the origin of the KBO color bimodality based on our survey results.