First results from video spectroscopy of 1998 Leonid meteors

We report spectroscopic observations of meteors made from the FISTA aircraft on 1998 November 17 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 Perseid meteors 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 Na than of other elements, an effect which is not observed in the Perseid meteors. Relative bulk abundances of Mg, Fe, Ca, and Na in Leonid meteors are nearly CI-chondritic within the uncertainty of the method (factor of 3). Smaller meteoroids tend to be poorer in Na which is true also for Perseid meteors. 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 N-2, even at high altitudes and in faint meteors. These emissions are therefore not connected with the meteor shock wave. Thermal continuum is also present in the spectra. Organic material was not revealed.