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Astron. Astrophys. 357, 1115-1122 (2000)

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1. Introduction

In our paper on meteoroid atmospheric fragmentation (Ceplecha et al. 1993), we recognized that most of the photographically recorded meteoroids (double- or multi-station records) behaved according to the single body theory with constant ablation and shape-density coefficients throughout the entire trajectory. About 40% of the studied cases with precision better than [FORMULA] m for one measured distance along the meteor trajectory exhibited no fragmentation (NF), another 40% exhibited one gross-fragmentation at one point (1F), and about 20% fragmented consecutively at more than one point (MF). The formalistic gross-fragmentation solution for these MF cases was found to be "unrealistic", i.e. the solution usually called for adding mass to the main body at a point instead of releasing part of mass as fragments. We were aware that some of the MF cases with "unrealistic" solutions may not be only due to more fragmentation points, but rather reflect some changes of the ablation and shape-density coefficients ([FORMULA] and K). In order to study these two coefficients as function of time, we need to use very precise records with distances along the trajectory (and heights) derived with precision of about [FORMULA] m. We also noted that going to few observations with higher precision, we were not able to apply the gross-fragmentation model at all: both the realistic and the "unrealistic" solutions yielded systematic time dependence of residuals.

In this paper we will derive a complete general solution of the single body theory with ablation coefficient, [FORMULA], and shape-density coefficient, K, both as function of time. We will then apply this solution to the most precise photographic observations of meteor trajectories available, in order to derive time change of ablation and shape-density coefficients. We were able to find 22 photographic meteors with such high precision of their records. In all 22 cases we were able to find numerical solutions with precision corresponding to the high precision of geometrically derived data. The smallest standard deviation for one measured point among these 22 cases was found [FORMULA] m; there are 7 cases with standard deviation of [FORMULA] m or lower; majority of standard deviations of the used meteors is between [FORMULA] m and [FORMULA] m.

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© European Southern Observatory (ESO) 2000

Online publication: June 5, 2000