Spectral analysis of two Perseid meteors

Spectra of two bright ( −11 mag) Perseid meteors are studied. Monochromatic light curves are constructed and the spectra are analyzed at selected points along the trajectory. The shift of maxima of low excitation iron lines down the trajectory in meteor flares is observed and explained by a longer radiative lifetime of the upper levels for these lines. Two spectral components with the temperatures of 4400–4800 K and 10,000 K, respectively, are identified in the spectra in accordance with previous findings. The ratio of both components, in terms of mass, varied 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 depends on the previous evolution of ablation. The abundances of heavy elements are found consistent with the chemical composition of carbonaceous 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 are estimated at 40 and 80 g, respectively. The meteor V-band luminous efficiency is found to vary in the range log τv = −11.8 to −12.0 in 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 Ca II lines and 1 % in all other lines between 3500 and 6600 Å.