A Correlation between Inclination and Color in the Classical Kuiper Belt

We have measured broadband optical BVR photometry of 24 Classical andScattered Kuiper belt objects (KBOs), approximately doubling the publishedsample of colors for these classes of objects. We find a statisticallysignificant correlation between object color and inclination in the ClassicalKuiper belt using our data. The color and inclination correlation increases insignificance after the inclusion of additional data points culled from allpublished works. Apparently, this color and inclination correlation has notbeen more widely reported because the Plutinos show no such correlation, andthus have been a major contaminant in previous samples. The color andinclination correlation excludes simple origins of color diversity, such as thepresence of a coloring agent without regard to dynamical effects.Unfortunately, our current knowledge of the Kuiper belt precludes us fromunderstanding whether the color and inclination trend is due to environmentalfactors, such as collisional resurfacing, or primordial population effects. Aperihelion and color correlation is also evident, although this appears to be aspurious correlation induced by sampling bias, as perihelion and inclinationare correlated in the observed sample of KBOs.Comment: Accepted to Astrophysical Journal Letter