The near-infrared spectrum of meteors.

Abstract

Photographic records of meteor spectra in the infrared were first secured in 1950 (Millman 1953) and by the end of 1958, seven Perseid meteors had been photographed at Canadian stations on fast Eastman infrared emulsions. Two infrared spectra photographed at the Springhill Meteor Observatory on August 12, 1958 confirm features previously identified in earlier spectra showing less detail. The better of the two Springhill spectra is of a Perseid with a visual magnitude -5, and shows a detail of 47 atomic emission lines, 33 in the visible region and 14 in the wave length range 7000-9000A. Using the multiplet table by Moore (1945) all the infrared lines have been satisfactorily identified with four nitrogen multiplets, Ni (I), (2), (3), (8), two oxygen multiplets Oi (I), (4), and a multiplet of ionized calcium Caii (2). The visible region of the spectrum shows lines of Hi, Nai, Mgi, Mgii, Sii, Siii, Cai, Caii, Fei, Feii and corresponds to the normal spectrum for bright Perseid meteors. The meteor was recorded on both high and low power radars working at 32 Mc/s, and produced an echo that lasted for over 200 seconds. The visual persistent train had a duration of 30 seconds. Heights for this meteor were determined by combining the photographic position with the radar range data. The photographed trail extended from a height of 104 km to 79 km with a bright burst at 84 km. The first feature to appear in the spectrum at the beginning of the trail was the neutral oxygen multiplet at 7774A. The lines of the ionized elements gained steadily in relative strength along the trail, reaching peak relative intensity at the burst, where Caii was the strongest feature. REFERENCES Millman, P. M. 1953, Nature 172, 853. Moore, C. E. 1945, Princeton Obs. Pub. No. 20. National Research Council Ottawa, Ont., Canada and Dominion Observatory Ottawa, Ont., Canada