• N. J. Papadopoulos

      Articles written in Journal of Astrophysics and Astronomy

    • Comparing maps to symplectic integrators in a galactic type Hamiltonian

      N. D. Caranicolas N. J. Papadopoulos

      More Details Abstract Fulltext PDF

      We obtain thex - pxPoincare phase plane for a two dimensional, resonant, galactic type Hamiltonian using conventional numerical integration, a second order symplectic integrator and a map based on the averaged Hamiltonian. It is found that all three methods give good results, for small values of the perturbation parameter, while the symplectic integrator does a better job than the mapping, for large perturbations. The dynamical spectra are used to distinguish between regular and chaotic motion.

    • Report on the dynamical evolution of an axially symmetric quasar model

      N. J. Papadopoulos N. D. Caranicolas

      More Details Abstract Fulltext PDF

      The role of the angular momentum in the regular or chaotic character of motion in an axially symmetric quasar model is examined. It is found that, for a given value of the critical angular momentumLzc, there are two values of the mass of the nucleusMn for which transition from regular to chaotic motion occurs. The [Lzc– Mn] relationship shows a linear dependence for the time independent model and an exponential dependence for the evolving model. Both cases are explained using theoretical arguments together with some numerical evidence. The evolution of the orbits is studied, as mass is transported from the disk to the nucleus. The results are compared with the outcomes derived for galactic models with massive nuclei.

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