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B. Gladman, C. Chan, E. Nadal (Univ. of British Columbia, CANADA)
The extended scattered disk consists of the trans-neptunian objects (TNOs) on highly eccentric orbits with perihelia so large that emplacement onto those orbits via repeated gravitational interactions with the current giant planets on their current orbits is implausible. The objects 2000 CR 105 and 2003 VB 12 are two standard examples of this structure, although other known TNOs also appear to belong to this structure. The characteristic feature is a large perihelion distance (typically, above q=38 AU) but (1) q depends on semimajor axis and (2) mean-motion resonances with the giant planets allow some particular semimajor axes to have their perihelia be temporarily raised as well.
Using massive numerical integrations, we have mapped the inner boundaries of the extended scattered disk to determine a practical stability boundary over the lifetime of the Solar System and examined the erosion rate of this structure. We show that the 4.5-Gyr stability boundary is in poor agreement with a map of chaotic behaviour at large semimajor axes; that is, there are large regions of chaotic behaviour that do not result in orbital instability over the age of the Solar System. We have also explored formation scenarios and have identified a perihelion-raising mechanism that is both natural in the context of giant planet formation, very efficient, and seems to match the observationally-determined facets of the extended scattered disk.
This work has been generously supported by the Canadian NSERC, CRC, and CFI funding agencies.
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Bulletin of the American Astronomical Society, 36 #4
© 2004. The American Astronomical Soceity.