New type of radiation of bright Leonid meteors above 130 km

Abstract

Abstract— In this paper, we study the extremely high beginning parts of atmospheric trajectories of seven Leonid meteors recorded by sensitive TV systems equipped with image intensifiers up to apparent magnitude +6.5. For all seven cases, we observed comet‐like diffuse structures with sizes on the order of kilometers that developed quickly during the meteoroids' descent through the atmosphere. For the brightest event with a maximum absolute magnitude of −12.5, we observed an arc similar to a solar protuberance and producing a jet detectable several kilometers sideways from the brightest parts of the meteor head, and moving with a velocity over 100 km/s. These jets are common features for the seven studied meteors. Precise position in trajectory, velocity, and brightness at each point is available for all seven meteors, because of double‐station records on 85 km base‐line. When these meteoroids reached 130 km height, their diffuse structures of the radiation quickly transformed to the usual meteor appearance resembling moving droplets, and meteor trains started to develop. These meteor phenomena above 130 km were not recognized before our observations, and they cannot be explained by standard ablation theory.

Bright Perseid fireball with exceptional beginning height of 170 km observed by different techniques

“…The wake is visible from 112.5 km. It closely resembles the behavior of Leonids described in Spurný et al (2000b). The altitude where the ablation starts to be the dominant source of light should be clearly visible in the part of the light curve where the slope of the light curve changes significantly (Koten et al 2006).…”

“…The maximum radiometric brightness is then −9.7 at the height of 82.7 km and corresponds to a short flare at 22:29:46.6637 ± 0.0005 s UT (mean time of maximum intensity from nine independent radiometric records) that is not resolved in photographic records. Spurný et al (2000b) divided the appearance of high-altitude meteors into three distinct phases: diffuse, intermediate, and sharp. Diffuse structures, observed above 130 km, are connected with sputtered particles and their subsequent thermalization.…”

“…It was confirmed and extended by Spurný et al (2000a), who reported beginning heights of 1998 Leonids up to 199 km, depending on initial mass and the observing system. Spurný et al (2000b) analyzed the radiation type of the highest Leonid meteors and suggested that light emitted above 130 km is probably not connected with thermal ablation. All high-altitude meteors from their sample showed cometlike diffuse structures above 130 km, which evolved into typical moving droplets at normal heights.…”

PF191012 Myszyniec – highest Orionid meteor ever recorded

“…This was quickly confirmed by Spurný et al (2000a), who reported several 1998 Leonid fireballs with beginning heights at 150−200 km. Spurný et al (2000b) analyzed the radiation type of the highest Leonid meteors and suggested that light emitted over 130 km might be due to processes not connected with ablation. All high-altitude meteors from their sample showed comet-like diffuse structures above 130 km, which evolved into typical moving droplets at normal heights.…”

“…All high-altitude meteors from their sample showed comet-like diffuse structures above 130 km, which evolved into typical moving droplets at normal heights. Spurný et al (2000b) divided the light curves of high-altitude meteors into three distinct phases: diffuse, intermediate, and sharp. The sharp phase was connected with well-known ablation processes.…”