The structure and evolution of "asteroidal" meteor swarms.

The structure of a meteor swarm at any moment of time depends on the orbital elements of the parental body (PB), on the PB position in the orbit, on the velocity and direction of meteor particles (MP) ejection. After choosing certain orbital elements and PB position in the orbit, as well as some average velocities of MP isotropic ejection, the authors calculate probable distributions of MP orbital elements depending upon the swarm age. It is shown that a compact and more stable meteor swarm corresponds to the PB orbit at aphelion. The swarm being ejected at the velocity of the order of 1 - 1,5 km/s at perihelion during 20 - 30 thousands years will take the form of a void toroid, the volume of which increases with time. The concentration of particles in the swarm gradually decreases thus causing the reduction of the probability of the Earth's collision with an abundant meteor flux.