ON THE EFFECT OF GIANT PLANETS ON THE SCATTERING OF PARENT BODIES OF IRON METEORITE FROM THE TERRESTRIAL PLANET REGION INTO THE ASTEROID BELT: A CONCEPT STUDY

摘要

In their model for the origin of the parent bodies of iron meteorites, Bottke et al. proposed differentiated planetesimals, formed in 1-2?AU during the first 1.5?Myr, as the parent bodies, and suggested that these objects and their fragments were scattered into the asteroid belt as a result of interactions with planetary embryos. Although viable, this model does not include the effect of a giant planet that might have existed or been growing in the outer regions. We present the results of a concept study where we have examined the effect of a planetary body in the orbit of Jupiter on the early scattering of planetesimals from the terrestrial region into the asteroid belt. We integrated the orbits of a large battery of planetesimals in a disk of planetary embryos and studied their evolutions for different values of the mass of the planet. Results indicate that when the mass of the planet is smaller than 10?M ⊕, its effects on the interactions among planetesimals and planetary embryos are negligible. However, when the planet mass is between 10 and 50?M ⊕, simulations point to a transitional regime with ~50 M ⊕ being the value for which the perturbing effect of the planet can no longer be ignored. Simulations also show that further increase of the mass of the planet strongly reduces the efficiency of the scattering of planetesimals from the terrestrial planet region into the asteroid belt. We present the results of our simulations and discuss their possible implications for the time of giant planet formation.