Artikel,
Iron, calcium, and potassium atom densities in the trails of Leonids and other meteors: Strong evidence for differential ablation
METEORITICS & PLANETARY SCIENCE, 34 (6): 1017-1027 (November 1999)
Zusammenfassung
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.
