SPECTRAL-ANALYSIS OF 2 PERSEID METEORS

Spectra of two bright (-11 mag) Perseid meteors are studied. Monochrom atic light curves are constructed and the spectra are analyzed at sele cted points along the trajectory. The shift of maxima of low excitatio n iron lines down the trajectory in meteor flares is observed and expl ained by a longer radiative lifetime of the upper levels for these lin es. Two spectral components with the temperatures of 4400-4800K and 10 ,000K, respectively, are identified in the spectra in accordance with previous findings. The ratio of both components, in terms of mass, var ied smoothly from about 100:1 over 15:1 to 30:1. This ratio is not an unambiguous function of meteor velocity, height and brightness but dep ends on the previous evolution of ablation. The abundances of heavy el ements are found consistent with the chemical composition of carbonace ous chondrites and the dust of comet Halley. Hydrogen, however, is not more abundant than in carbonaceous chondrites and thus significantly less than in cometary dust. The initial masses of the two meteoroids a re estimated at 40 and 80 g, respectively. The meteor V band luminous efficiency is found to vary in the range log tau(v) = -11.8 to -12.0 i n magnitude c.g.s. units. For the panchromatic luminous efficiency use of the value of -11.4 for bright Perseids is recommended. Nearly 1.5% of meteoroid kinetic energy is radiated out in the Call lines and 1% in all other lines between 3500 and 6600 Angstrom. (C) 1997 Elsevier S cience Ltd.