Collisional and dynamical evolution of Plutinos

G. C. DE ELÍA, A. BRUNINI, AND R. P. DI SISTO

ASTRONOMY AND ASTROPHYSICS

EDP SCIENCES S A

Lugar: Paris; Año: 2008 vol. 490 p. 835 - 842

0004-6361

Aims. In this paper, we analyze the collisional and dynamical evolution of the population of Plutinos.Methods. To do this, we test different collisional parameters and include a dynamical treatment that takes into account the stabilityand instability zones of the 3:2 mean motion resonance with Neptune. This procedure allows us to estimate the size distribution ofPlutinos, to study their mean collisional lifetimes, to analyze the formation of families, to obtain ejection rates of fragments from theresonance and to discuss their possible contribution to the ecliptic comet population. Our simulations are developed assuming theexistence of one Pluto-sized object in the 3:2 Neptune resonance.Results. The Plutino population larger than a few kilometers in diameter is not significantly altered by catastrophic collisions overthe age of the Solar System. Thus, we infer that the break suggested by previous works at a diameter D near 40−80 km in thePlutino cumulative size distribution should be primordial and not a result of the collisional evolution. The existence of such a breakis still a matter of debate. On the other hand, our analysis indicates that one large family was formed in the 3:2 Neptune resonanceover the Solar System history. Concerning Plutino removal, we find that one object with a diameter D > 1 km is ejected from the3:2 resonance with Neptune every ∼300−1200 yr. Then, we study the sensitivity of our results to the number of Pluto-sized objectsin the 3:2 Neptune resonance. Our simulations suggest that the larger the number of Pluto-sized bodies, the higher the ejection rateof fragments from that resonant region and the number of families formed over 4.5 Gyr. Thus, if a maximum of 5 Pluto-sized objectsare assumed to be in the 3:2 Neptune resonance, one body with a diameter D > 1 km is ejected every tens of years while ∼30 largefamilies are formed over the Solar System history. From these estimates, we conclude that it is necessary to specify the number ofPluto-sized objects present in the 3:2 Neptune resonance to determine if this region can be considered an important source of eclipticcomets. Finally, we find that the current orbital distribution of the Plutinos does not offer a strong constraint on the dynamical originof this population.