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B.J. Gladman (Obs. de la Cote d'Azur), M. Holman (Harvard-Smithsonian CfA), T. Grav (Univ. of Oslo), J. Kavelaars (McMaster Univ. Canada), P. Nicholson (Cornell), K. Asknes (Univ. of Oslo), J-M. Petit (Obs. de Besancon)
By telescopic tracking, we have established the orbits of several trans-neptunian objects (TNOs) with perihelia in the range 40-44 AU, but with semimajor axes > 50 AU. These orbits are thus outside the domain controlled by very strong gravitational close encounters with Neptune. Because these objects are on large eccentric orbits, they must have been placed on them by a gravitational perturbation other than close gravitational scattering caused by any of the giant planets (on their current orbits). We present the results of numerical simulations which show that the emplacement of objects scattered by the giant planets into orbits such as these is extremely inefficient. The existence of the discovered objects may thus have profound cosmogonic implications for our understanding of the formation of the outer Solar System. We discuss some viable scenarios which could have produced these objects, including long-term diffusive chaos, scattering off of other massive bodies in the outer Solar System, or encounters with passing stars. This discovery implies that there must be a large population of trans-neptunian objects in an `extended scattered disk' with perihelia above the previously-discussed boundary of perihelia q=34-38 AU.