Structure and evolution of the asteroid belt

Abstract

AbstractInvestigations concerning the structure of the asteroid belt make it possible to distinguish four main stages in its evolution. The first stage. The formation of a certain number of protoplanets (ten-hundred) between the orbits of Mars and Jupiter, simultaneously with major planets. The protoplanets had the dimensions of the presently largest asteroids. The peculiarity of their orbits consisted of a predominance of large inclinations. The second stage. The unstable “primary” asteroid belt which came into existence as a result of mutual collisions of the protoplanets and occupied the zone with daily mean motion between 300 and 990″. Numerous close encounters of asteroids with Jupiter. The formation of planets having unusual orbits (Hidalgo, the Trojans and others). The formation of a wide gap (300–540″) which separated the stable asteroid belt from Jupiter’s orbit. The third stage. The stable asteroid belt in the zone 540–990″. The predominance of planets of “the spherical” subsystem. The formation of gaps corresponding to “acute” commensurabilities in mean motions with Jupiter. The fourth stage. The present asteroid belt occupying the zone 450–1110″. The asteroid belt gradually expanded in the direction towards the Sun. The bulk of young planets concentrating in the ecliptic plane. The total mass of the asteroid belt during the time of its existence has decreased to a fraction of its former value.