RENOIR: Probing the Surface Transformation of Centaurs via Color Photometry

Centaurs are small bodies residing on unstable orbits between Jupiter and Neptune. As objects recently scattered from their sources in the Kuiper belt and beyond, they carry the compositional information of their parent populations into the realm of the giant planets. Unlike the TNO populations, Centaurs are known for possessing an unusual bimodal distribution of optical surface colors, splitting them into two distinct groups - red and grey (neutral). It has been long disputed whether this color distribution points to Centaurs being sources from two distinct formation locations in the TNOs populations, or alternatively that the present surface color distribution represents an ongoing dynamical-evolutionary pathway experienced by Centaurs that produces the two groups. Here we present results from a broadband visible photometric investigation using the g', r' and i' filters of 20 Centaurs obtained with the Gemini Observatories. The data have been collected as a part of the RENOIR (Revealing cENtaur cOlor hIstoRy) survey in 2022-2024. The goal of our program is to collect surface colors of Centaurs covering a wide range of diameters and occupying the entire heliocentric distance span of the Centaur region. We will investigate the distribution of colors across the Centaur region as functions of heliocentric distance and object diameter; also examining the potential Centaur surface-color transformation as a function of an object’s recent dynamical history. We will compare our results with other studies and recent JWST observations.