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DISCOVERY OF THE FIRST RETROGRADE TRANSNEPTUNIAN OBJECT

2009; IOP Publishing; Volume: 697; Issue: 2 Linguagem: Inglês

10.1088/0004-637x/697/2/l91

1538-4357

Brett Gladman, J. J. Kavelaars, Jean-Marc Petit, M. L. N. Ashby, J. W. Parker, J. Coffey, Lynne Jones, P. Rousselot, O. Mousis,

Stellar, planetary, and galactic studies

We report the discovery of the first transneptunian object known to be on a retrograde orbit. The discovery was made during an outer solar system survey using the Canada–France–Hawaii Telescope (CFHT). After recovery observations on the MMT, CTIO-Blanco, Gemini-South, and CFHT telescopes, we can state with certainty that the object is both transneptunian and orbits the Sun in a retrograde sense, with an orbital inclination i = 104 deg. The object has IAU Minor Planet Center provisional designation 2008 KV42 and temporary nickname "Drac." Numerical integration of a set of initial states consistent with the astrometry shows that the semimajor axis is a ≃ 42 AU, the perihelion distance is q∼21 AU, and that the object's orbit evolves on ∼30 million year timescales via gravitational encounters with Uranus and Neptune. The object is unlikely to be primordial and thus needs a supply mechanism from a long-lived source. We outline several scenarios which could have emplaced the object on its current orbit, including a currently unobserved reservoir of large-inclination orbits beyond Neptune which may also supply the Halley-type comets.