Meteor shower features: are they governed by the initial formation process or by subsequent gravitational perturbations?

Abstract

The fine-structure properties found in a meteoroid stream determine what is observed in the associated meteor shower. These properties depend both on the ejection process of meteoroids from their parent body and on the subsequent orbital evolution which is determined by gravitational perturbations and radiation effects. Until about 30 years ago computing capabilities were not large enough to allow the integration of orbits of a significant number of meteoroids, therefore in practice it was impossible to combine an initial ejection process and follow the effects of perturbations. Computing capabilities have improved dramatically and the question of whether the structure that is present in streams today is determined primarily by the ejection process or by the subsequent orbital evolution can be considered. No single answer can be expected to the question that is the subject of our investigation. In some cases a structure introduced into the stream by the ejection process will survive to be observable today, in others it will not. We thus proceed by reviewing much of the previously published work that is relevant to this problem and we also produce some new results on the Geminid and Quadrantid streams.