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J.A. Fernandez, T. Gallardo (Depto. Astronomia, Facultad de Ciencias, Montevideo, Uruguay), A. Brunini (Facultad de Ciencias Astronomicas y Geofisicas, La Plata, Argentina - CONICET)
We numerically study the dynamical evolution of the 76
Scattered Disk Objects (SDOs), discovered through the end of
2002, plus 399 clones for 5 Gyr. We are particularly
interested in analyzing the frequency with which the
perihelion distances of SDOs raise above 40 AU. We found
that the Kozai mechanism (coupling between the argument of
perihelion, eccentricity, and inclination) is the main
responsible for raising both the perihelion distance and the
inclination. The highest perihelion distance for a body of
our sample was found to be q=62.1 AU, which shows that
bodies can be decoupled from the planetary region by
dynamical interactions with the planets, without need to
invoke cosmogonic causes or external perturbers (close
stellar passages). We find that about 12% of our sample
objects acquire q>40 AU (with semimajor axes a>60 AU) at
some time of their evolution, with a mean lifetime in that
dynamical state of ~ 1.3 Gyr. We also analyze the
probability that the SDOs fall in one of the following end
states: reaching Jupiter's influence zone, hyperbolic
ejection, or transfer to the Oort cloud. We find that nearly
50% of the SDOs are transferred to the Oort cloud, from
which about 60% have their perihelia beyond Neptune's orbit
(31
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Bulletin of the American Astronomical Society, 36 #2
© 2004. The American Astronomical Soceity.