63 citations · 240 across the 15 of their papers we have counts for
15 papers
Periodic orbits in a near Yang-Mills potential
George Contopoulos, Mirella Harsoula
We consider the orbits in the Yang-Mills (YM) potential V=1/2 x2 y2 and in the potentials of the general form Vg=1/2 [α (x2 +y2)+x2 y2]. The stable period-9 (number of intersection…
Perturbed precessing ellipses as the building blocks of spiral arms in a barred galaxy with two pattern speeds
M. Harsoula, C. Efthymiopoulos, G. Contopoulos +1
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…
Precessing ellipses as the building blocks of spiral arms
M. Harsoula, K. Zouloumi, C. Efthymiopoulos +1
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 g…
Manifold spirals in barred galaxies with multiple pattern speeds
C. Efthymiopoulos, M. Harsoula, G. Contopoulos
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 manifo…
Characteristic times in the standard map
Mirella Harsoula, Kostas Karamanos, George Contopoulos
We study and compare three characteristic times of the standard map, the Lyapunov time t_L, the Poincare recurrence time t_r and the stickiness (or escape) time t_{st}. The Lyapuno…
Global and Local diffusion in the Standard Map
Mirella Harsoula, George Contopoulos
We study the global and the local transport and diffusion in the case of the standard map, by calculating the diffusion exponent . In the global case we find that the mean diffu…