The First Retrograde Transneptunian Object
Résumé
We report the discovery of the first trans-neptunian object known to be on a retrograde heliocentric orbit. The object , with internal survey designation HL8n1 and Minor Planet Center provisional designation 2008 KV32, was discovered at CFHT on May 31/2008 and tracked through July 8/2008 using the MMT 6.5-m, the CTIO-Blanco 4-m, and the Gemini-South 8-m telescopes. Given all current astrometry, three different orbital fitting methods confirm that the object is retrograde (i=103.6 +/- 0.2 degrees) and the that semimajor axis is roughly 45 AU (with 40 - 60 AU still being allowed). The object appears to have a perihelion distance near 20 AU, and orbital integrations indicate dynamical lifetimes of order 300 Myr. Production of such an orbit from known mechanisms and sources is unlikely; the spectrum of possibilities will be discussed given the orbital information available.