Discovery of a Candidate Inner Oort Cloud Planetoid

We report the discovery of the minor planet 2003 VB12 (popularly namedSedna), the most distant object ever seen in the solar system. Pre-discoveryimages from 2001, 2002, and 2003 have allowed us to refine the orbitsufficiently to conclude that 2003 VB12 is on a highly eccentric orbit whichpermanently resides well beyond the Kuiper belt with a semimajor axis of480$\pm$40 AU and a perihelion of 76$\pm$4AU. Such an orbit is unexpected inour current understanding of the solar system, but could be the result ofscattering by a yet-to-be-discovered planet, perturbation by an anomalouslyclose stellar encounter, or formation of the solar system within a cluster ofstars. In all of these cases a significant additional population is likelypresent, and in the two most likely cases 2003 VB12 is best considered a memberof the inner Oort cloud, which then extends to much smaller semimajor axes thanpreviously expected. Continued discovery and orbital characterization ofobjects in this inner Oort cloud will verify the genesis of this unexpectedpopulation.Comment: to be published in ApJL, 10 August 200