{1} Ondrejov Observatory, Astronomical Institute of the Academy of Sciences,
251 65 Ondrejov, Czech Republic
{2} Institute for Dynamics of Geospheres, Russian Academy of Sciences,
Leninsky pr. 38, build. 6, Moscow 117979, Russia
Abstract. The unique observational spectrum of the very bright
Benesov bolide EN 070591 is compared to theoretical bolide spectra.The
-19.5 mag bolide was induced by a meteoroid of an estimated initial mass
of 4000 kg, a density of 2 g/cm^3 and a kinetic energy of 10^12 J (0.2
kT TNT). The ablating piston model predicts spectra of large bolides by
radiative hydrodynamics calculations. We present examples of the calculated
H-chondrite vapor spectral opacities and of the resulting spectra for various
parameters.
Both theoretical and observed spectra show that bolide radiation is
composed of atomic line emissions, molecular bands and continuum radiation.
The role of the continuum increases with increasing meteoroid size and
with decreasing altitude. The atomic lines are produced under the effective
excitation temperature of 4000-6000 K.
The lines of Fe I are too faint and the lines of Ca I are too bright
in the model in comparison with the observations. Also the computed continuum
level is too high. These differences can be explained by the fact that
the vapors occupy a larger volume and have lower density than predicted.
This is probably a consequence of a mutual interaction of fragments after
the meteoroid fragmentation and of a not well understood ablation process.
Other differences between the theory and the observation are described
and possible model improvements are discussed.
Key words: meteoroids, meteors
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