We study the regular or chaotic character of orbits in a 3D dynamical model,describing a triaxial galaxy surrounded by a spherical dark halo component. Ournumerical experiments suggest that the percentage of chaotic orbits decreasesexponentially as the mass of the dark halo increases. A linear increase of thepercentage of the chaotic orbits was observed as the scale length of the halocomponent increases. In order to distinguish between regular and chaoticmotion, we chose to use the total angular momentum Ltot of the 3D orbits as anew indicator. Comparison with other, previously used, dynamical indicators,such as the Lyapunov Characteristic Exponent or the P(f) spectral method, showsthat the Ltot indicator gives very fast and reliable results for characterizingthe nature of orbits in galactic dynamical models.
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