Fragmentation model of meteoroid motion, mass loss, and radiation in the atmosphere

Abstract

Abstract-We present the basic differential equations of meteor physics (the single body equations). We solve them numerically including two possible types of fragmentation: into large pieces and into a cluster of small fragments. We have written a Fortran code that computes the motion, ablation and light intensity of a meteoroid at chosen heights, and allows for the ablation and shape density coefficients σ and K, as well as the luminous efficiency τ, to be variable with height/time. We calibrated our fragmentation model (FM) by the best fit to observational values for the motion, ablation, radiation, fragmentation and the terminal masses (recovered meteorites) for the Lost City bolide. The FM can also handle multiple and overlapping meteor flares. We separately define both the apparent and intrinsic values of σ, K, and τ. We present in this paper values of the intrinsic luminous efficiency as function of velocity, mass, and normalized air density. Detailed results from the successful application of the FM to the Lost City, Innisfree, and Benešov bolides are also presented.Results of applying the FM to 15 bolides with very precise observational data are presented in a survey mode (Table 7). Standard deviations of applying our FM to all these events correspond to the precision of the observed values. Typical values of the intrinsic ablation coefficient are low, mostly in the range from 0.004 to 0.008 s 2 km −2 , and do not depend on the bolide type. The apparent ablation coefficients reflect the process of fragmentation. The bolide types indicate severity of the fragmentation process. The large differences of the "dynamic" and "photometric" mass from numerous earlier studies are completely explained by our FM. The fragmentation processes cannot be modeled simply by large values of the apparent ablation coefficient and of the apparent luminous efficiency. Moreover, our new FM can also well explain the radiation and full dynamics of very fast meteoroids at heights from 200 km to 130 km.

Infrasound and seismic detections associated with the 7 September 2015 Bangkok fireball

“…The hypersonic entry of meteroids generates infrasonic waves which are refracted and channelled over long distances by the temperature gradient and the wind structure of the atmosphere (Kulichkov 2004;). In most instances, the atmosphere slows down, breaks up, and even vaporize meteoroids, producing a meteor (Ceplecha and Revelle 2005). A particularly strong shock wave can be generated by explosive fragmentation of the meteoroid in one or several airbursts (Ceplecha and Revelle 2005;Edwards et al 2008).…”

“…In most instances, the atmosphere slows down, breaks up, and even vaporize meteoroids, producing a meteor (Ceplecha and Revelle 2005). A particularly strong shock wave can be generated by explosive fragmentation of the meteoroid in one or several airbursts (Ceplecha and Revelle 2005;Edwards et al 2008). Infrasound measurements may provide crucial information about trajectory and energy for events [e.g., Brown et al (2013);Pilger et al (2015)].…”

Evidence for a meteoritic origin of the September 15, 2007, Carancas crater

“…Using a drastic simplification, a massive body penetrating the atmosphere with a velocity considerably greater than the speed of sound instantaneously looses a large part of its kinetic energy during ablation process (Ceplecha et al 2005). It suffers such a strong deceleration that it fragments before reaching the ground surface.…”

The Carancas meteorite impact crater, Peru: Geologic surveying and modeling of crater formation and atmospheric passage

“…The following values are used in the model: a density of 3700 kg/m 3 (Consolmagno et al 1998); an ablation coefficient of 0.004-0.008 s 2 /km 2 (Ceplecha and ReVelle 2005); a drag coefficient of 0.5 (typical for a sphere) and 0.85 (typical for a blunt body); an entry velocity of 14 km/s (higher or lower velocity leads to obvious changes in dynamic pressure). Preatmospheric mass, and entry angle were varied to find a combination that resulted in a transient crater size which Fig.…”