TWO COLOR POPULATIONS OF KUIPER BELT AND CENTAUR OBJECTS AND THE SMALLER ORBITAL INCLINATIONS OF RED CENTAUR OBJECTS

Abstract

ABSTRACT We present new optical colors for 28 Kuiper Belt objects (KBOs) and 35 Centaur objects measured with the 1.8 m Vatican Advanced Technology Telescope and the 4.3 m Discovery Channel Telescope. By combining these new colors with our previously published colors, we increase the sample size of our survey to 154 objects. Our survey is unique in that the uncertainties in our color measurements are less than half the uncertainties in the color measurements reported by other researchers in the literature. Small uncertainties are essential for discerning between a unimodal and a bimodal distribution of colors for these objects as well as detecting correlations between colors and orbital elements. From our survey, it appears red Centaurs have a broader color distribution than gray Centaurs. We find red Centaurs have a smaller orbital inclination angle distribution than gray Centaurs at the 99.3% confidence level. Furthermore, we find that our entire sample of KBOs and Centaurs exhibits bimodal colors at the confidence level. KBOs and Centaurs with H V > 7.0 have bimodal colors at the 99.96% confidence level and KBOs with H V < 6.0 have bimodal colors at the 96% confidence level.