Journal Article

Asymptotic orbits in barred spiral galaxies

M. Harsoula, C. Kalapotharakos and G. Contopoulos

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 411, issue 2, pages 1111-1126
Published in print February 2011 | ISSN: 0035-8711
Published online February 2011 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2010.17748.x
Asymptotic orbits in barred spiral galaxies

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We study the formation of the spiral structure of barred spiral galaxies, using an N-body model. The evolution of this N-body model in the adiabatic approximation maintains a strong spiral pattern for more than 10 bar rotations. We find that this longevity of the spiral arms is mainly due to the phenomenon of stickiness of chaotic orbits close to the unstable asymptotic manifolds originated from the main unstable periodic orbits, both inside and outside corotation. The stickiness along the manifolds corresponding to different energy levels supports parts of the spiral structure. The loci of the disc velocity minima (where the particles spend most of their time, in the configuration space) reveal the density maxima and therefore the main morphological structures of the system. We study the relation of these loci with those of the apocentres and pericentres at different energy levels. The diffusion of the sticky chaotic orbits outwards is slow and depends on the initial conditions and the corresponding Jacobi constant.

Keywords: galaxies: kinematics and dynamics; galaxies: spiral; galaxies: structure

Journal Article.  9113 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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