The Dynamics of Known Centaurs

We have numerically investigated the long term dynamical behavior of knownCentaurs. This class of objects is thought to constitute the transitionalpopulation between the Kuiper Belt and the Jupiter-family comets (JFCs). In ourstudy, we find that over their dynamical lifetimes, these objects diffuse intothe JFCs and other sinks, and also make excursions into the Scattered Disk, but(not surprisingly) do not diffuse into the parameter space representing themain Kuiper Belt. These Centaurs spend most of their dynamical lifetimes inorbits of eccentricity 0.2-to-0.6 and perihelion distance 12-to-30 AU. Theirorbital evolution is characterized by frequent close encounters with the giantplanets. Most of these Centaurs will escape from the solar system (or enter theOort Cloud), while a fraction will enter the JFC population and a few percentwill impact a giant planet. Their median dynamical lifetime is 9 Myr, althoughthere is a wide dispersion in lifetimes, ranging from less than 1 Myr to morethan 100 Myr. We find the dynamical evolution of this sample of Centaurs to beless orderly than the planet-to-planet "hand-off" described in previousinvestigations. We discuss the implications of our study for the spatialdistribution of the Centaurs as a whole.Comment: 13 pages, 11 figures, revised version in press at A