Dynamical evolution and end states of scattered disk objects

FERNANDEZ, J. A.; GALLARDO, T.; BRUNINI, A.

Los Angeles,USA.

Congreso; 35# Annual Meeting of the DDA of the AAAS; 2004

AAAS

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<q<36 AU) at the moment of reaching the Oort cloud.