Iron, calcium, and potassium atom densities in the trails of Leonids and other meteors: Strong evidence for differential ablation

Abstract

Abstract— We report on studies of the Fe, Ca, and K atom densities in the trails of meteors. The measurements of the densities were taken simultaneously and in a common volume by three ground‐based lidars. We report and analyze the data obtained during two nights of Leonid showers (1996 and 1998 November 16/17) and of one night five days after the 1998 Leonids. The lidar‐observed trails of Leonids differ from those of other meteor showers in both their mean altitude and in mean metal composition. The Leonid trails show a highly depressed Ca/Fe abundance ratio in comparison to CI meteoritic composition.Our observations are interpreted with the help of a numerical model that describes the ablation processes occurring during the high‐speed entry of meteoroids into the Earth's atmosphere. We conclude that for the lidar‐observed meteoroids, the ablation process occurs differentially for the three elements. This leads to a mixture of metals in the meteor trails, the composition of which is strongly altitude dependent and at any one altitude deviates significantly from a CI meteoritic composition. The model predicts differing altitudes and durations of trail observations for different showers, allowing us to tentatively assign the origin to the observed trails.