Adrián Brunini

Collisional and dynamical evolution of the L

Aims. In this paper, we analyze the collisional and dynamical evolution of the population of L 4 Jovian Trojans. Methods. To do this, we test different collisional parameters and include a dynamical treatment, taking into account the stability and instability zones of the L 4 Trojan swarm. This procedure allows us to estimate the size distribution of the L 4 Trojans, to study their mean collisional lifetimes, to analyze the formation of families, to obtain ejection rates of Trojan fragments and to discuss their possible contribution to the current populations of Centaurs and Jupiter-family comets. Results. Our estimates of the L 4 Trojan cumulative size distribution show waves that propagate from diameters of ~0.1 to ~80xa0km around the values derived from optical surveys. On the other hand, the mean collisional lifetimes obtained from our simulations indicate that the large Trojan asteroids have likely survived without being catastrophically fragmented over the age of the Solar System. With regards to the Trojan removal, we calculate a maximum ejection rate of Trojan fragments fromxa0 L 4 of ~50xa0objects larger than 1 km of diameter per Myr, which results to be significantly smaller than values previously published. Such estimates allow us to infer that the contribution of the Trojan asteroids to the current populations of Centaurs and Jupiter-family comets is negligible. In addition, our results are in agreement with the formation of few Trojan families in the L 4 swarm. On the other hand, we infer that the current orbital distribution of the Trojan asteroids does not offer a strong constraint on the dynamical origin of this population.

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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 stability and instability zones of the 3:2 mean motion resonance with Neptune. This procedure allows us to estimate the size distribution of Plutinos, to study their mean collisional lifetimes, to analyze the formation of families, to obtain ejection rates of fragments from the resonance and to discuss their possible contribution to the ecliptic comet population. Our simulations are developed assuming the existence 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 over the age of the Solar System. Thus, we infer that the break suggested by previous works at a diameter D near 40−80 km in the Plutino cumulative size distribution should be primordial and not a result of the collisional evolution. The existence of such a break is still a matter of debate. On the other hand, our analysis indicates that one large family was formed in the 3:2 Neptune resonance over the Solar System history. Concerning Plutino removal, we find that one object with a diameter D > 1 km is ejected from the 3:2 resonance with Neptune every ∼300−1200 yr. Then, we study the sensitivity of our results to the number of Pluto-sized objects in the 3:2 Neptune resonance. Our simulations suggest that the larger the number of Pluto-sized bodies, the higher the ejection rate of fragments from that resonant region and the number of families formed over 4.5 Gyr. Thus, if a maximum of 5 Pluto-sized objects are 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 large families are formed over the Solar System history. From these estimates, we conclude that it is necessary to specify the number of Pluto-sized objects present in the 3:2 Neptune resonance to determine if this region can be considered an important source of ecliptic comets. Finally, we find that the current orbital distribution of the Plutinos does not offer a strong constraint on the dynamical origin of this population.

Trojan asteroids

Abstract We present numerical results obtained by a simulation of the collisional process between asteroids and scattered comets from the Uranus–Neptune zone. This mechanism allows the use of single exponent incremental size distributions for the initial belt reaching a final distribution that matches the observed population very well. Since the cometary bombardment was extremely efficient removing mass from the primordial asteroid belt in a very short time, we always obtained belts with total masses less than 0.001 M⊕ after ≈ 2×107 yrs. This result allows processes with an important initial mass preserving Vestas basaltic crust.

Collisional and dynamical evolution of Plutinos

Abstract We study the dynamical evolution of the Hilda group of asteroids trough numerical methods, performing also a collisional pseudo-evolution of the present population, in order to calculate the rate of evaporation and its contribution to the cratering history of the Galilean satellites. If the present population of small asteroids in the Hildas region follows the same size distribution observed at larger radii, we find that this family is the main contributor to the production of small craters (i.e., crater with diameters d ∼4xa0km) on the Galilean system, overcoming the production by Jupiter Family Comets and by Trojan asteroids. The results of this investigation encourage further observational campaigns, in order to determine the size distribution function of small Hilda asteroids.

COLLISIONAL EVOLUTION OF THE EARLY ASTEROID BELT

Aims. We analyze the jovian Trojan dust in the L4 swarm. Methods. To do this, we use a modification of the numerical code developed by us and previously applied to the collisional and dynamical evolution of the L4 jovian Trojans. This algorithm considers catastrophic collisions and cratering events, includes a dynamical treatment that takes the stability and instability zones of the L4 jovian swarm into account, and incorporates the effects of the Poynting-Robertson radiation. Results. From this analysis, we infer that the time evolution of the L4 jovian Trojan dust luminosity has the characteristics of a diffusion process, since its current value is fairly insensitive to variations in the initial size distribution. Moreover, our results indicate that the current luminosity of the dust in the L4 jovian swarm ranges from ∼3.2 × 10 −8 to 3.4 × 10 −8 L� . Conclusions. From these estimates, we conclude that the current luminosity of the dust in the L4 jovian swarm is comparable to the luminosity of the inner Solar System dust, and, at least, one order of magnitude lower than the luminosity of the outer Solar System dust.

Cratering rate on the jovian system: the contribution from Hilda asteroids

We analyze the process of planetary scattering around M0-type stars. To do this, we carry out N-body simulations with three Jupiter-mass planets close to their instability limit together with an outer planetesimal disk. This paper focuses on the analysis of systems in which a single Jupiter-mass planet survives after the dynamical instability event. The small body reservoirs show different dynamical behaviors. In fact, our simulations produce particles on prograde and retrograde orbits, as well as particles whose orbital plane flips from prograde to retrograde and back again along their evolution. Such particles are called Type-F particles. We find strong correlations between the inclination

Studying the jovian Trojan dust

i

Effects of an eccentric inner Jupiter on the dynamical evolution of icy body reservoirs in a planetary scattering scenario

and the ascending node longitude

Terrestrial planets and water delivery around low-mass stars

Omega

Migrating Jupiter up to the habitable zone: Earth-like planet formation and water delivery

of such particles. First,