Abstract. Detailed analysis of one of the largest and well documented
bolides -- the Benesov bolide (EN 070591) -- has been performed. The bolide
had an initial velocity of 21 km/s, reached a maximal absolute magnitude
of -19.5 at the altitude of 24 km and radiated down to 17 km. Detailed
photographic data for the light curve, geometry and dynamics of the main
body and several fragments are available. This enabled us to test the theoretical
radiative-hydrodynamic model used previously for the analysis of satellite-detected
bolides.
The conventional analysis produces a huge discrepancy between the dynamic
(80-300 kg) and photometric (5000-13,000 kg) mass. The discrepancy might
be removed assuming a low density of 0.5 g/cm^3 but this is unrealistic.
The radiative-hydrodynamic modeling yielded a mass of 2000 kg and density
of 1-2 g/cm^3. However, the dynamics was not sufficiently well reproduced.
There is direct observational evidence of meteoroid fragmentation at
altitudes of 38-31 km and of catastrophic disruption at 24 km. These, however,
do not explain the problem with the mass. The crucial point is that the
bolide was significantly decelerated already at the altitudes between 50-40
km, while enormous luminosity was produced below 40 km. We suggest that
the meteoroid must have been fragmented into 10-30 pieces of an mass of
100-300 kg already at altitude of 60-50 km. By creating a progressive fragmentation
model with two types of fragmentation at three different altitude levels,
we were able to reproduce the dynamics and luminosity sufficiently well.
The best estimate of the initial mass is 3000-4000 kg for a density of
2 g/cm^3.
The comparison with the bolide PN 39434 suggests that the behavior
of Benesov is typical for large stony meteoroids. Early fragmentation under
dynamic pressures of the order of 1 Mdyn/cm^2 is very important. The analysis
of the light curve with the radiative-hydrodynamic model can give good
order-of-magnitude estimates of mass, if no dynamic data are available.
Key words: meteoroids, meteors
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