Collisional and Dynamicla evolution of the L4 Troyan asteroids

DE ELIA, G. BRUNINI, A.

ASTRONOMY AND ASTROPHYSICS

EDP Sciences

Lugar: Les Ulis; Año: 2007 vol. 475 p. 375 - 389

0004-6361

Aims. In this paper, we analyze the collisional and dynamical evolution of the population of L4 Jovian Trojans.Methods. To do this, we test different collisional parameters and include a dynamical treatment, taking into account the stabilityand instability zones of the L4 Trojan swarm. This procedure allows us to estimate the size distribution of the L4 Trojans, to studytheir mean collisional lifetimes, to analyze the formation of families, to obtain ejection rates of Trojan fragments and to discuss theirpossible contribution to the current populations of Centaurs and Jupiter-family comets.Results. Our estimates of the L4 Trojan cumulative size distribution show waves that propagate from diameters of ∼0.1 to ∼80 kmaround the values derived from optical surveys. On the other hand, the mean collisional lifetimes obtained from our simulationsindicate that the large Trojan asteroids have likely survived without being catastrophically fragmented over the age of the SolarSystem. With regards to the Trojan removal, we calculate a maximum ejection rate of Trojan fragments from L4 of ∼50 objects largerthan 1 km of diameter per Myr, which results to be significantly smaller than values previously published. Such estimates allow usto infer that the contribution of the Trojan asteroids to the current populations of Centaurs and Jupiter-family comets is negligible. Inaddition, our results are in agreement with the formation of few Trojan families in the L4 swarm. On the other hand, we infer that thecurrent orbital distribution of the Trojan asteroids does not offer a strong constraint on the dynamical origin of this population.