2 COMPONENTS IN METEOR SPECTRA

Through an analysis of fireball spectra it was found that meteor heads consist of two parts with quite different temperatures. The spectra of both parts can be fitted with a simple thermal equilibrium model. The temperature of the main spectrum is about 4000 K, and that of the second spectrum is about 10,000 K. There is little evidence for a dependence of temperatures on the meteor velocity. However, the mass and luminosity of the second part relative to the main part grows rapidly with meteor velocity. The high temperature part forms only 0.02% of the meteor vapor envelope in slow meteors but accounts for more than 5% in fast meteors. In fast meteors most of the light is produced in this part, mainly by the CaII lines. This fact influences the meteor luminous efficiency and color index. The traditional classification of meteor spectra reflects the variable intensity of the second spectrum. In the high temperature region the density is also enhanced. This region is very probably related to the meteor shock wave.