Chaotic diffusion and the origin of comets from the 2/3 resonance in the Kuiper Belt

The dynamical structure of the 2/3 resonance at small inclination is explored using numerical integrations of test particles to compute the evolution of proper elements with time. The basic features are related to the analytically computed geography of secular resonances. This paper focuses on the existence of slowly diffusing chaotic orbits, which escape from the 2/3 resonance after billions of years. The origin of short-period comets may be related to the existence of such orbits. We numerically determine the rate at which 2/3 resonant objects are delivered to close encounters with Neptune. From this result we estimate the number of comet-sized objects that should presently be in the 2/3 resonance to explain the influx rate of observed short period comets; the result of 10(8) to 10(9) seems to imply that 2/3 resonant bodies should be collisionally evolved. (C) 1997 Academic Press.