Some New Results and Perspectives Regarding the Kuiper Belt Object Arrokoth's Remarkable, Bright Neck.

One of the most striking and curious features of the small Kuiper Belt Object (KB), Arrokoth, explored by New Horizons, is the bright, annular neck it exhibits at the junction between its two lobes. Here we summarize past reported findings regarding the properties of this feature and report new findings regarding its dimensions, reflectivity and color, shape profile, and its lack of identifiable craters. We conclude by enumerating possible origin scenarios for this unusual feature. New results include a new measurement of the observed neck area of 8+/-1.5 km2, a total neck surface area of 32 km2, a 12.5:1 ratio of neck circumference to height, a normal reflectance histogram of the observed neck, and the fact that no significant (i.e., >2 sigma) color units were identified, meaning the neck's color is generally spatially uniform at the 1.5 km/pixel scale of the best color images. Although several origin hypotheses for the bright material in the neck are briefly discussed, none can be conclusively demonstrated to be the actual origin mechanism at this time; some future tests are identified.