  The Centaurs are a transient population of small bodies in the outer solar
system whose orbits are strongly chaotic. These objects typically suffer
significant changes of orbital parameters on timescales of a few thousand
years, and their orbital evolution exhibits two types of behaviors described
qualitatively as random-walk and resonance-sticking. We have analyzed the
chaotic behavior of the known Centaurs. Our analysis has revealed that the two
types of chaotic evolution are quantitatively distinguishable: (1) the random
walk-type behavior is well described by so-called generalized diffusion in
which the rms deviation of the semimajor axis grows with time t as ~t^H, with
Hurst exponent H in the range 0.22--0.95, however (2) orbital evolution
dominated by intermittent resonance sticking, with sudden jumps from one mean
motion resonance to another, has poorly defined H. We further find that these
two types of behavior are correlated with Centaur dynamical lifetime: most
Centaurs whose dynamical lifetime is less than ~22 Myr exhibit generalized
diffusion, whereas most Centaurs of longer dynamical lifetimes exhibit
intermittent resonance sticking. We also find that Centaurs in the diffusing
class are likely to evolve into Jupiter-family comets during their dynamical
lifetimes, while those in the resonance-hopping class do not.
