Diffuse Structure of Some Meteors at the Beginning of Their Trajectories at Classical Heights

Аннотация

The problem of anomalous meteors with diffuse view and increased size of their comas at the beginning of radiation is considered. Results from processing some meteors detected with high-sensitive observational TV systems of the Super-Isocon type during Leonid storm observations in 2002 are given. As opposed to similar cases described in literature previously, the given meteors had an increased in size diffuse structure of the meteor coma not at extra-high altitudes but below 128 km: 118.06 ± 0.07 km, 123.01 ± 0.02 km, and 124.45 ± 0.10 km. At the trajectory beginning, their absolute stellar magnitudes varied in the range of +6^m to +5^m, and they reached –0.5^m in maximum of brightness. The range of their masses was 0.03–0.06 g. The influence of the TV system’s working mode on the possible appearance of artifacts is considered. While the transparent, diffuse view of a limiting low-light meteor image can be a result of a low signal-to-noise ratio, the increase in spatial size of a meteor coma cannot be explained by technical artifacts. Separation of some extremely low-light meteor images in start frames onto a range of individual point-like objects placed inside a zone of 0.5–1.5 km can serve as an indirect argument for real fragmentation of an initial particle. A conclusion is drawn about the possible fragmentation of some meteoroids from the Leonid stream during a time period of 2–3 weeks before collision with the Earth with velocities of fragment separation on the order of millimeters a second.