Chaos maps as tools to explore meteoroid streams dynamics

Abstract

Asteroids and comets can both eject streams of meteoroids. If those meteoroids stay on similar orbits and then encounter the Earth, the resulting meteors are visible in our night sky as a series of bright lines seemingly originating from a single point: a meteor shower. If the link between the meteor shower observed and the parent body is definitely proven, any information about the meteor shower can lead to some interesting results on the parent body. This link can be quite complex to establish, as dynamical chaos can play a role in the evolution of meteoroid stream between the ejection from the parent body and the final encounter with the Earth. Dynamical chaos is characterized by the exponential divergence in time of two initially almost identical orbits. In order to study the amount of chaos in meteoroid stream, we have used the well-known method of chaos maps. They are drawn using a chaos indicator, which measures the level of chaos for a specific set of orbital elements. We chose to use the orthogonal fast Lyapunov indicator (see Fouchard et al., 2002). Thanks to these maps, we detect several key features in meteoroid streams. We started by studying the Geminids, the Draconids and the Leonids, three well-known and well-defined meteoroid steams, with widely different orbits (near-Earth orbit, similar to Jupiter-family comet and similar to Halley-type comet, respectively) (see Courtot et al., 2023, 2024). Despite these very different orbital environment, some mechanisms can be found in all three cases: the effect of mean-motion resonances is similar. These resonances with a specific planet capture meteoroids thus preventing them from encountering the planet, forming islands of relative stability. The planets affected by this mechanism are Venus and the Earth for the Geminids, and Jupiter for the Draconids and Leonids. Non-gravitational forces (Poynting-Robertson drag and solar radiation pressure) influence heavily the dynamical evolution of small particles (see Vaubaillon et al., 2005). In the case of the Geminids, we were able to detect the escape of small particles from the capture of mean-motion resonances, but this does not happen for the Draconids and Leonids, because the effect of those forces is much weaker in these regions and the mean-motion resonances are much wider (see again Courtot et al., 2023, 2024).We also studied the Taurids, a less well-known meteroid stream. Here, the link between the supposed parent body of the stream and the observed meteors is not so clear and discussions on the origin of the stream are still ongoing. Despite the similarity with the Geminids in terms of orbits, the Taurids present very different chaos maps, where the effect of mean-motion resonances is much weaker. However, other phenomena can be studied and then compared to the results obtained for the three previous streams. This talk aims to present these results and the next steps on this topic.