Speaker:

B.M. Shustov, R.V. Zolotarev (Institute of Astronomy of the Russian Academy of Sciences)

Title:

THE MASS INDEX OF METEOR BODIES AND THE EVOLUTION OF METEOROID STREAMS

Abstract:

It is known from observations that the mass spectra of meteor bodies (meteoroids) causing the phenomena of sporadic meteors and bodies in meteor showers in differential form are close to dN µ M^-sdM, and the mass index is s ~ 2 in the case of sporadic meteors and s < 2 (1.5-1.8) for meteor showers. We have analyzed the reasons for this difference. We believe that the value of the s = 2 index reflects the random nature of the formation of meteoroid flows, both as a result of the decay of comets and during collisions of asteroids and larger meteoroids. The deviation of the index value from 2 reflects the influence of the further evolution of meteoroid flows. The purpose of the work is to study this evolution.

The report describes the procedure for determining the velocity field of particles of various masses leaving the comet nucleus. We consider an ensemble of particles of various sizes in a range of sizes (masses) that allow using the most abundant radar and optical data for determining the mass spectrum of meteoroids. The results of calculations of the evolution of meteoroid flows obtained with the REBOUND software package are presented. It is shown that a distribution of mass spectra is formed in the meteoroid stream: in the center of the stream, the mass index values are less than 2, at the edge of the stream may exceed 2. There are two reasons for such changes in the structure of the meteoroid stream: 1) the initial velocity of the ejection of particles from the comet nucleus strongly depends on the particle size and more “high-speed” small particles are faster removed from the nuclei, and 2) small particles are more susceptible to the action of radiation forces and therefore disperse in space faster than large ones, and, accordingly, the value of the mass index in the center of the flow decreases. These results are consistent with the results obtained by other authors from observations of meteor showers, in particular, the Arietid meteor shower.

References:

1. B. M. Shustov and R. V. Zolotarev, Mass Indices of Meteoric Bodies:
2. Formation Model of Meteoroid Streams // Astronomy Reports, 2022, Vol. 66, No. 2, pp. 179–189.
3. R. V. Zolotarev and B. M. Shustov, Mass Indices of Meteoric Bodies:
4. Evolution of Meteoroid Streams // Astronomy Reports, 2022, Vol. 66, No. 3, pp. 255–268.