Simulations of the population of Centaurs - I. The bulk statistics

Abstract

Large-scale simulations of the Centaur population are carried out. The evolution of 23 328 particles based on the orbits of 32 well-known Centaurs is followed for up to 3 Myr in the forward and backward direction under the influence of the four massive planets. The objects exhibit a rich variety of dynamical behaviour with half-lives ranging from 540 kyr (1996 AR20) to 32 Myr (2000 FZ53). The mean half-life of the entire sample of Centaurs is 2.7 Myr. The data are analysed using a classification scheme based on the controlling planets at perihelion and aphelion, previously given in Horner et al. Transfer probabilities are computed and show the main dynamical pathways of the Centaur population. The total number of Centaurs with diameters larger than 1 km is estimated as ∼44 300, assuming an inward flux of one new short-period comet every 200 yr. The flux into the Centaur region from the Edgeworth-Kuiper Belt is estimated to be one new object every 125 yr. Finally, the flux from the Centaur region to Earth-crossing orbits is one new Earth-crosser every 880 yr.

The bimodal colors of Centaurs and small Kuiper belt objects

“…Although SDOs are frequently considered as the main source of Centaurs, we note that Neptune Trojans, Plutinos, and classical KBOs have also been found to be viable contributors (Horner & Lykawka 2010;Yu & Tremaine 1999;Volk & Malhotra 2008, respectivelly). Furthermore, Centaurs possess short dynamical lifetimes of ∼5 × 10 5 −3 × 10 7 yr before being injected as JFCs or ejected again into the outer solar system (Horner et al 2004). If some surface evolution mechanism, dependent on heliocentric distance, is responsible for the bimodal behavior of Centaurs, it must be acting extremely rapidly such that no intermediate colors are ever seen among them.…”

Giant comets and mass extinctions of life

“…The mean dynamical lifetime L d of Centaurs was found to decline strongly with perihelion distance, with L d <10 Myr for objects with q ≤17 au, down to 7.6 Myr for bodies with 5.2< a <30 au and ∼6.2 Myr for Centaurs defined as Q <40 au and a <29 au. Horner et al (2004aHorner et al ( , 2004b obtained L d ∼2.7 Myr for a sample of Centaurs defined by the latter criteria.…”

A portrait of the extreme solar system object 2012 DR30

“…Following a procedure established in earlier works (Horner et al 2004a;Horner & Lykawka 2010;Horner et al 2012a,b) we created a suite of test particles distributed in even sized steps across the 3-sigma error ellipses of the objects best-fit orbit in perihelion distance, q, eccentricity, e, and inclination, i. In this way, we created a grid of 45 × 45 × 45 = 91 125 test particles in q-e-i space, centred on the nominal best-fit orbit for 2012 DR 30 .…”