Fireball fragmentation in the first half of the atmospheric trajectory
Lukáš Shrbený, Pavel Spurný, Jiří Borovička
Planetary and Space Science
In Press, Journal Pre-proof, Available online 1 May 2020
• Results on the fragmentation of fireballs in the first half of their atmospheric trajectory are presented. The fragmentation demonstrates itself by the formation of wakes.
• Wakes in the early parts of the trajectory were observed for PE type I and II fireballs only and under very small dynamic pressures 0.004–0.062 MPa.
• The observed maximum length of wake is a linear function of the length passed by the point-like meteor from the beginning of its atmospheric trajectory down to the height of the wake creation. We do not know any obvious reason for this dependency.
• Light curves could be described by quasi-continuous fragmentation with mass of eroded dust from 10−8 to 10−2 kg. The beginnings of wakes correspond to the fragmentation point determined from the fragmentation model.
• Space weathering is proposed as a source of cementing of asteroidal material and thus increasing its strength from 25 Pa to more than 5 kPa.”
“We present direct video observations of fragmentation in the first half of the atmospheric trajectory of several fireballs recorded with the Czech part of the European Fireball Network. The fragmentation takes place in the form of wakes. In this work we describe heights, velocities, and sizes of meteoroids, deduced from our Digital Autonomous Fireball Observatories, where these wakes form and disappear, and lengths of wakes from our video records. We compare derived fireball parameters with values derived on the basis of light curve modeling. The aim of the work is to determine the type of fragmentation and propose its possible source. The observed dynamic pressures at these fragmentation points are of the order of 0.01 MPa. Observed flow regimes indicate that the creation of wakes may be triggered by the meteor shock wave. Quasi-continuous fragmentation was determined as the responsible type of fragmentation in the first half of the atmospheric trajectory by our model.”