Critical Ergos Curves and Chaos at Corotation
The theory of adiabatic invariants is developed to cover the gyration of a star about a nearly equipotential orbit in a galaxy with a strong bar. The guiding centres for such orbits follow curves of constant Ergos. The energy and the gyration adiabatic invariant give two constants of the motion. Critical Ergos curves have a pair of X-type gravitational neutral points which provide switches between trajectories that have the star circulating forward or backward relative to the corotating frame of the bar and those that liberate back to remain on one side of the galaxy’s centre.
An attempt to discover the dynamical basis of the apparently random switching, that has been observed in computations of orbits with finite amplitudes of gyration, FAILS to find any such chaos at small gyration amplitudes, where Ergos curves give a good description of guiding centre motion.
KeywordsSaddle Point Drift Velocity Adiabatic Invariant Drift Trajectory Random Switching
Unable to display preview. Download preview PDF.