CAOSP abstracts, Volume: 35, No.: 3, year: 2005

Abstract: The activity of the Perseid stream in the range of photographic meteors is reviewed. An attention is paid to the activity of the stream close to the parent-comet return in 1991 to 1994, characteristics of the so-called new maximum and two different dust components - blanket in the present node of the comet and a ribbon-like structure, named as Nodal Blanket (Jenniskens et al., 1998) and Perseid Filament (Lindblad and Porubčan, 1994), respectively.

A fine structure of the Perseid stream and its filaments is studied using the method of indices - the procedure based only on mathematical statistics. In the study the new completed 2003 version of the IAU Meteor Data Center catalogue of precise photographic orbits (Lindblad et al., 2005) is employed. 560 (64%) of 875 Perseids taken into account were sorted out to 17 filaments found. The selected filaments are not distributed in the space accidentally, but they form higher structures consisting of 1 individual filament, 3 branches of the stream containing 9 filaments together and a central part of the stream. In the central part of Perseids, 3 branches and 1 individual filament were identified. The structures are dived into a cloud of 315 dispersed orbits.

Positions of 17 filaments are compared with strong mean-motion resonances with Jupiter and Saturn. The existence of gaps in the distribution of the semimajor axes of the Perseids is confirmed using the considerably more numerous material.