J. Borovicka, R. Stork, and J. Bocek
Astronomical Institute of the Academy of Sciences of the Czech Republic, 251 65 Ondrejov Observatory, The Czech Republic
Abstract.
We report spectroscopic observations of meteors made from the FISTA
aircraft on November 17, 1998 as a part of the Leonid Multi-Instrument
Aircraft Campaign. Low resolution spectra of 119 meteors of apparent visual
magnitudes from +3 to -4, corresponding to meteoroid masses from
10-6 to 10-3
kg, were obtained. After analyzing a representative sample of the spectra and
comparing them to the spectra of Perseids from the Ondrejov archive, the
following conclusions were reached: Leonid meteoroids are very loose and
disintegrate easily in the atmosphere. This leads to much faster evaporation
of volatile sodium than of other elements, an effect which is not observed in
Perseids. Relative bulk abundances of Mg, Fe, Ca, and Na in Leonids are
nearly CI-chondritic within the uncertainty of the method (factor of three).
Smaller meteoroids tend to be poorer in sodium, which is true also for
Perseids. Most meteoric vapor emissions could be reasonably well explained
with the temperature of 4500 K. High temperature meteoric emissions
(Ca+,Mg+)
are present only in bright meteors. Leonid spectra are very rich in
atmospheric emissions of O, N, and N2 - even at high altitudes and in faint
meteors. These emissions are therefore not connected with meteor shock wave.
Thermal continuum is also present in the spectra. Organic material was not
revealed.
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