Quantifying Chaos in Models of the Solar Neighbourhood

TL;DR

This paper introduces a new technique to quantify chaos in models of the Solar neighbourhood, revealing that models with both bar and spiral perturbations exhibit strong chaos, influencing local velocity distributions.

Contribution

A novel chaos quantification method applied to Solar neighbourhood models, demonstrating the impact of bar and spiral resonances on chaos levels and local velocity structures.

Findings

Models with bar and spiral perturbations show strong chaos.

The highest chaos occurs where bar and spiral resonances overlap.

The bar-only model remains largely regular.

Abstract

{} {To quantify the amount of chaos that exists in the local phase space.} {A sample of orbits from four different models of the Solar neighbourhood phase space are analysed by a new chaos identification (and quantification) technique. While three of the used models bear the signature of the perturbation due to both the Galactic bar and the spiral pattern, the last of the models is a bar only one. We explore the models by inter-comparing the corresponding values of chaos strength that is induced at the various energy levels .}{(1) We find that of all the viable models that have been demonstrated to successfully reproduce the local phase space structure, i.e. those that include the bar as well as the spiral, bear strong chaoticity, though the model that implies the highest degree of chaos is the one in which overlap of the major resonances of the bar and the spiral occurs. The bar only model is found to display regularity. (2) We advance chaos to be primarily responsible for the splitting of the Hyades-Pleiades mode (the larger mode) of the local velocity distribution}{}