Dynamical evolution and end states of active and inactive Centaurs

Abstract

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 ($=1.37 \times 10^6$ 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 ($\sim 10^2-10^3$ yr), while such drops are not found among inactive Centaurs. Inactive Centaurs with $T_J \lsim 2.5$ usually evolve to Halley-type comets, whereas inactive Centaurs with $T_J \gsim 2.5$ and active Centaurs (that also have $T_J \gsim 2.5$) 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.