Characterisation of chaos and mean-motion resonances in meteoroid streams -- Application to the Draconids and Leonids

Abstract

Context. Dynamically linking a meteor shower with its parent body is challenging, and chaos in the dynamics of meteoroid streams may be one of the reasons. For a robust identification of parent bodies, it is therefore necessary to quantify the amount of chaos involved in the evolution of meteoroid streams. Aims. The characterisation of chaos in meteoroid streams thanks to chaos maps is still a new field of study. We aim to study two very different meteoroid streams, the Draconids and the Leonids, in order to obtain a general view of this topic. Methods. We use the method developed in a previous paper dedicated to Geminids, drawing chaos maps with the orthogonal fast Lyapunov indicator. We choose four particle size ranges to investigate the effect of non-gravitational forces. As the dynamics is structured by mean-motion resonances with planets, we compute the locations and widths of the resonances at play. We use semi-analytical formulas valid for any eccentricity and inclination and an arbitrary number of planets. Results. We pinpoint which mean-motion resonances with Jupiter play a major role in the dynamics of each meteoroid stream. We show how those resonances tend to trap mostly large particles, preventing them from meeting with Jupiter. We also study particles managing to escape those resonances, thanks to the gravitational perturbation of Saturn for example. Finally, we explain why non-gravitational forces do not disturb the dynamics much, contrary to what is observed for the Geminids.