Decay of the O I λ5577 line in meteor wakes

Abstract

Multiple-exposure spectra of six meteors showing the auroral green line of atomic oxygen have been measured photometrically. The decay of the green line is described in terms of two parameters which are given as functions of height. It is shown that the maximum intensity occurs after a measurable time interval, which varies from 0.3 s at 115 km to 0.06 s at 105 km and decreases further with decreasing height. The subsequent decay rate is close to the natural rate (1 s−1) of the 1S state above 110 km, but increases with decreasing height to 3 s−1 at 100 km. The height of the green-line emission is consistent with most previous measurements, and corresponds with the height of the atmospheric atomic oxygen layer. The observations do not show a correlation of green-line characteristics with geomagnetic activity. Various possible excitation and quenching mechanisms are discussed.