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We study the transfer process from the scattered disk (SD) to the high-perihelion scattered disk (HPSD) (defined as the population with perihelion distances q > 40 AU and semimajor axes a > 50 AU) by means of two different models. One model (Model 1) assumes that SD objects (SDOs) were formed closer to the Sun and driven outwards by resonant coupling with the accreting Neptune during the stage of outward migration (Gomes 2003b, Earth, Moon, Planets 92, 29-42.). The other model (Model 2) considers the observed population of SDOs plus clones that try to compensate for observational discovery bias (Ferna´ndez et al. 2004, Icarus, in press). We find that the Kozai mechanism (coupling between the argument of perihelion, eccentricity, and inclination), associated with a mean motion resonance (MMR), is the main responsible for raising both the perihelion distance and the inclination of SDOs. The highest perihelion distance for a body of our samples was found to be q ¼ 69:2 AU. This shows that bodies can be temporarily detached from the planetary region by dynamical interactions with the planets. This phenomenon is temporary since the same coupling of Kozai with a MMR will at some point bring the bodies back to states of lower-q values. However, the dynamical time scale in high-q states may be very long, up to several Gyr. For Model 1, about 10% of the bodies driven away by Neptune get trapped into the HPSD when the resonant coupling Kozai-MMR is disrupted by Neptune's migration. Therefore, Model 1 also supplies a fossil HPSD, whose bodies remain in non-resonant orbits and thus stable for the age of the solar system, in addition to the HPSD formed by temporary captures of SDOs after the giant planets reached their current orbits. We find that about 12-15% of the surviving bodies of our samples are incorporated into the HPSD after about 4-5 Gyr, and that a large fraction of the captures occur for up to the 1:8 MMR (a ' 120 AU), although we record captures up to the 1:24 MMR (a ' 260 AU). Because of the Kozai mechanism, HPSD objects have on average inclinations about 25 -50 , which are higher than those of the classical Edgeworth-Kuiper (EK) belt or the SD. Our results suggest that Sedna belongs to a dynamically distinct population from the HPSD, possibly being a member of the inner core of the Oort cloud. As regards to 2000 CR 105 , it is marginally within the region occupied by HPSD objects in the parametric planes ðq; aÞ and ða; iÞ, so it is not ruled out that it might be a member of the HPSD, though it might as well belong to the inner core.

We study the Kozai dynamics affecting the orbital evolution of transneptunian objects being captured or not in MMR with Neptune. We provide energy level maps of the type (ω, q) describing the possible orbital paths from Neptune up to semimajor axis of hundreds of AU. The dynamics for non resonant TNOs with perihelion distances, q, outside Neptune's orbit, a N , is quite different from the dynamics of TNOs with q < a N , already studied in previous works. While for the last case there are stable equilibrium points at ω = 0• , 90• , 180• and 270• in a wide range of orbital inclinations, for the former case it appears a family of stable equilibrium points only at a specific value of the orbital inclination, i ∼ 62• , that we call critical inclination. We show this family of equilibrium points is generated by a mechanism analogue to which drives the dynamics of an artificial satellite perturbed by an oblate planet. The planetary system also generates an oscillation in the longitude of the perihelion of the TNOs with i ∼ 46• , being Eris a paradigmatic case. We discuss how the resonant condition with Neptune modify the energy level curves and the location of equilibrium points. The asymmetric librations of resonances of the type 1:N generate a distortion in the energy level curves and in the resulting location of the equilibrium points in the phase space (ω, q). We study the effect on the Kozai dynamics due to the diffusion process in a that occurs in the Scattered Disk. We show that a minimum orbital inclination is required to allow substantial variations in perihelion distances once the object is captured in MMR and that minimum inclination is greater for greater semimajor axis.

We numerically study the dynamical evolution of observed samples of active and inactive Centaurs and clones that reach the Jupiter-Saturn region. Our aim is to compare the evolution between active and inactive Centaurs, their end states and their transfer to Jupiter family comets and Halley-type comets. We find that the median lifetime of inactive Centaurs is about twice longer than that for active Centaurs, suggesting that activity is related to the residence time in the region. This view is strengthened by the observation that high-inclination and retrograde Centaurs (Tisserand parameters with respect to Jupiter T J < 2) which have the longest median dynamical lifetime (= 1.37 × 10 6 yr) are all inactive. We also find that the perihelion distances of some active, comet-like Centaurs have experienced drastic drops of a few au in the recent past (∼ 10 2 − 10 3 yr), while such drops are not found among inactive Centaurs. Inactive Centaurs with T J < ∼ 2.5 usually evolve to Halley-type comets, whereas inactive Centaurs with T J > ∼ 2.5 and active Centaurs (that also have T J > ∼ 2.5) evolve almost always to Jupiter family comets and very seldom to Halley type comets. Inactive Centaurs are also more prone to end up as sungrazers, and both inactive and active Centaurs transit through different mean motion resonances (generally with Jupiter) during their evolution.