THE ORBITAL ELEMENTS OF A METEOROID AFTER ITS EJECTION FROM A COMET

This article examines the changes in the orbital elements of particles ejected from the nucleus of an active comet. We extend the work of Pl avec (1957) to include changes in all the orbital elements resulting f rom the ejection process. We take into account the constraints that mu st be met before a meteoroid particle can be observed as a meteor. In addition we constrain particle ejection to take place only on the sun- ward hemisphere of the cometary nucleus and only when the comet is les s than 1.88 AU from the Sun. For a given true anomaly of the ejection event, our equations allow the determination of the speed and directio n of the ejected particle. Using the ejection of particles from comet P/Swift-Tuttle, we applied our approach in an attempt to explain wheth er or not a new filament of activity first seen in 1986 could be attri buted to particles ejected from the comet near the time of its 1862 pe rihelion passage. Observed Perseid meteor rates in 1986 - 1995, expres sed as a function of the solar longitude, cannot be used to uniquely d etermine the time the corresponding particles were ejected from the pa rent comet. The observed meteor shower activity could have been caused by particles that were ejected from the nucleus at a variety of times , velocities and ejection angles.