Paper to be published in Meteoroitics & Planetary Science in November 1999

First results from video spectroscopy of 1998 Leonid meteors

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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