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WGN, the Journal of the IMO 27:2 (1999) 85 Ongoing Meteor Work

Summary: WGN, the Journal of the IMO 27:2 (1999) 85
Ongoing Meteor Work
Leonid Dust Trails and Meteor Storms
Robert H. McNaught and David J. Asher
Leonid storms are caused by the Earth intersecting dense trails of dust ejected from Comet 55P/Tempel­Tuttle.
Here, we extend existing studies by examining the higher ejection­velocity regions of young dust trails and the
circumstances around the 2031 return of 55P/Tempel­Tuttle. A model of dust trail density is successfully fitted
to the observed ZHR of storms. Based on this, predictions are made for encounters in the next few years and
around 2031, giving both the times and rates of maxima. The most likely prospects for encounters are from
1999--2002, especially 2001 and 2002. Details of a storm in 1869 are presented and confirm that the time of
maximum is predictable to 10 minutes accuracy or better. The consequences of these findings are applied to the
satellite threat and to the methods of global analysis of Leonid rates.
1. Introduction
Meteor storms occur when the Earth passes through dense trails of meteoroids and dust such as
those observed by the Infra­Red Astronomical Satellite [1]. The motion of Comet 55P/Tempel­
Tuttle only has relevance, with regard to Leonid storms, in defining the initial orbits of the
meteoroids at ejection. To understand Leonid activity requires a study of the perturbed motion
of these meteoroids. It has been known for some time [2--4] that perturbations can be significantly
different on Leonid meteoroids that are separated in mean anomaly. Extensive calculations about
swarm/trail encounters covering the 19th and 20th centuries were first done by Kondrat'eva et


Source: Armagh Observatory


Collections: Physics