Spatial Structure of Regular and Chaotic Orbits in Self-Consistent Models of Galactic Satellites |
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| Authors: | J C Muzzio M E Mosquera |
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| Institution: | (1) Facultad de Ciencias Astronómicas y Geofísicas, Instituto de Astrofísica La Plata (UNLP—CONICET), Universidad Nacional de La Plata, La Plata, Buenos Aires, 1900, Argentina |
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| Abstract: | In several previous papers we had investigated the orbits of the stars that make up galactic satellites, finding that many
of them were chaotic. Most of the models studied in those works were not self-consistent, the single exception being the Heggie
and Ramamani (1995) models; nevertheless, these ones are built from a distribution function that depends on the energy (actually,
the Jacobi integral) only, what makes them rather special. Here we built up two self-consistent models of galactic satellites,
freezed theirs potential in order to have smooth and stationary fields, and investigated the spatial structure of orbits whose
initial positions and velocities were those of the bodies in the self-consistent models. We distinguished between partially chaotic (only one non-zero Lyapunov exponent) and fully chaotic (two non-zero Lyapunov exponents) orbits and showed that, as could be expected from the fact that the former obey an additional
local isolating integral, besides the global Jacobi integral, they have different spatial distributions. Moreover, since Lyapunov
exponents are computed over finite time intervals, their values reflect the properties of the part of the chaotic sea they
are navigating during those intervals and, as a result, when the chaotic orbits are separated in groups of low- and high-valued
exponents, significant differences can also be recognized between their spatial distributions. The structure of the satellites
can, therefore, be understood as a superposition of several separate subsystems, with different degrees of concentration and
trixiality, that can be recognized from the analysis of the Lyapunov exponents of their orbits. |
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| Keywords: | chaotic motion galactic satellites stellar orbits |
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