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pro vyhledávání: '"Efthymiopoulos, C."'
Observations and simulations of barred spiral galaxies have shown that, in general, the spiral arms rotate at a different pattern speed to that of the bar. The main conclusion from the bibliography is that the bar rotates faster than the spiral arms
Externí odkaz:
http://arxiv.org/abs/2210.01479
Stable periodic orbits in spiral galactic models that form families of precessing ellipses can create spiral density waves similar to those that are observed in real grand-design galaxies. We study the range in parameter space for which the amplitude
Externí odkaz:
http://arxiv.org/abs/2109.01506
Publikováno v:
A&A 636, A44 (2020)
In the manifold theory of spiral structure in barred galaxies, the usual assumption is that the spirals rotate with the same pattern speed as the bar. Here we generalize the manifold theory under the assumption that the spirals rotate with different
Externí odkaz:
http://arxiv.org/abs/1910.06653
The manifold theory of barred-spiral structure provides a dynamical mechanism explaining how spiral arms beyond the ends of galactic bars can be supported by chaotic flows extending beyond the bar's co-rotation zone. We discuss its applicability to N
Externí odkaz:
http://arxiv.org/abs/1901.00692
Autor:
Christodoulidi, H., Efthymiopoulos, C.
We investigate the long term evolution of trajectories in the Fermi-Pasta-Ulam (FPU) system, using as a probe the first non--trivial integral $J$ in the hierarchy of integrals of the corresponding Toda lattice model. To this end we perform simulation
Externí odkaz:
http://arxiv.org/abs/1812.01924
Akademický článek
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Publikováno v:
MNRAS (December 01, 2016) 463 (2): 2210-2228
Using N-body simulations we study the structures induced on a galactic disc by repeated flybys of a companion in decaying eccentric orbit around the disc. Our system is composed by a stellar disc, bulge and live dark matter halo, and we study the sys
Externí odkaz:
http://arxiv.org/abs/1611.04891
We summarize various cases where chaotic orbits can be described analytically. First we consider the case of a magnetic bottle where we have non-resonant and resonant ordered and chaotic orbits. In the sequence we consider the hyperbolic Henon map, w
Externí odkaz:
http://arxiv.org/abs/1603.09515
We consider analytical formulae that describe the chaotic regions around the main periodic orbit $(x=y=0)$ of the H\'{e}non map. Following our previous paper (Efthymiopoulos, Contopoulos, Katsanikas $2014$) we introduce new variables $(\xi, \eta)$ in
Externí odkaz:
http://arxiv.org/abs/1502.00664
We consider normal forms in `magnetic bottle' type Hamiltonians of the form $H=\frac{1}{2}(\rho^2_\rho+\omega^2_1\rho^2) +\frac{1}{2}p^2_z+hot$ (second frequency $\omega_2$ equal to zero in the lowest order). Our main results are: i) a novel method t
Externí odkaz:
http://arxiv.org/abs/1501.07018