Mass Indices of Meteoric Bodies: I. Formation Model of Meteoroid Streams

It is known from observations that the mass spectra of meteoric bodies (meteoroids) that cause the phenomena of sporadic meteors and bodies in meteor showers are close in differential form to dN ∝ M –s dM , while the mass index s ≈ 2 for sporadic meteors and s < 2 (1.5−1.8) for meteor showers. We have analyzed the causes of this difference. We assume that the value of the index s ≈ 2 implies the randomness of the meteoroid stream formation both as a result of the decay of comets and of collisions of asteroids and larger meteoroids. The deviation of the index from 2 is due to the influence of the further evolution of meteoroid streams. This study considers the formulation of the first part of the problem of the evolution of the mass spectrum of bodies in meteoroid streams. This part refers to the determination of the velocity field of particles of various masses escaping the comet nucleus, i.e., substantiation of the choice of input parameters of the corresponding numerical model for calculating the further evolution of the meteoroid stream. An important feature is the consideration of an ensemble of particles of various sizes in the range of sizes (masses) that allow the use of the most abundant radar data on determining the meteoroid masses for comparison.