Colors of Centaurs observed by the Subaru/Hyper Suprime-Cam and implications for their origin

TL;DR

This study analyzes the surface colors of nine Centaurs using Subaru's Hyper Suprime-Cam, revealing similarities with high-inclination trans-Neptunian objects and providing insights into their origin and evolutionary history.

Contribution

It presents new color measurements of nine Centaurs and compares them with TNOs, highlighting their color distribution and correlations with orbital parameters, thus informing theories of their origin.

Findings

Centaurs' colors are similar to high-inclination TNOs.

Moderate positive correlation between Centaurs' color and semi-major axis.

No significant correlation between color and other orbital elements or magnitude.

Abstract

Centaurs have orbits between Jupiter and Neptune and are thought to originate from the trans-Neptunian region. Observations of surface properties of Centaurs and comparison with those of trans-Neptunian objects (TNOs) would provide constraints on their origin and evolution. We analyzed imaging data of nine known Centaurs observed by the Hyper Suprime-Cam (HSC) installed on the Subaru Telescope with the g and i band filters. Using the data available in the public HSC data archive as well as those obtained by the HSC Subaru Strategic Program (HSC-SSP) by the end of June, 2017, we obtained the g-i colors of the nine Centaurs. We compared them with those of known TNOs in the HSC-SSP data obtained by Terai et al. (2018). We found that the color distribution of the nine Centaurs is similar to that of those TNOs with high orbital inclinations, but distinct from those TNOs with low orbital inclinations. We also examined correlations between the colors of these Centaurs and their orbital elements and absolute magnitude. The Centaurs' colors show a moderate positive correlation with semi-major axis, while no significant correlations between the color and other orbital elements or absolute magnitude were found for these Centaurs. On the other hand, recent studies on Centaurs with larger samples show interesting correlations between their color and absolute magnitude or orbital inclination. We discuss how our data fit in these previous studies, and also discuss implications of these results for their origin and evolution.