Orbital dynamics of three-dimensional bars: II. Investigation of the parameter space

Academy of Athens, Athínai, Attica, Greece
Monthly Notices of the Royal Astronomical Society (Impact Factor: 5.11). 07/2002; DOI: 10.1046/j.1365-8711.2002.05469.x
Source: arXiv


We investigate the orbital structure in a class of 3D models of barred galaxies. We consider different values of the pattern speed, of the strength of the bar and of the parameters of the central bulge of the galactic model. The morphology of the stable orbits in the bar region is associated with the degree of folding of the x1-characteristic. This folding is larger for lower values of the pattern speed. The elongation of rectangular-like orbits belonging to x1 and to x1-originated families depends mainly on the pattern speed. The detailed investigation of the trees of bifurcating families in the various models shows that major building blocks of 3D bars can be supplied by families initially introduced as unstable in the system, but becoming stable at another energy interval. In some models without radial and vertical 2:1 resonances we find, except for the x1 and x1-originated families, also families related to the z-axis orbits, which support the bar. Bifurcations of the x2 family can build a secondary 3D bar along the minor axis of the main bar. This is favoured in the slow rotating bar case. Comment: 11 pages, 20 figures, 1 table, to appear in MNRAS

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Available from: Charalampos Skokos, Aug 05, 2013
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    • "Hamiltonian systems or symplectic mappings), in which new and more complicated phenomena are expected in higher dimensions. Hamiltonian systems with n≥2 degrees of freedom have been studied extensively in the context of celestial mechanics, especially with regard to problems of galactic dynamics [1] [2] [3] [4] [5] . "
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    ABSTRACT: We discuss the evolution of a disc galaxy due to the formation of a bar and, subsequently, a peanut. After the formation stage there is still considerable evolution, albeit slower. In purely stellar cases the pattern speed of the bar decreases with time, while its amplitude grows. However, if a considerable gaseous component is present in the disc, the pattern speed may increase with time, while the bar strength may decrease. In some cases the gas can be brought sufficiently close to the center to create a strong central concentration, which, in turn, may modify the properties of the bar. More violent evolution can take place during interactions, so that some disc substructures can be either formed or destroyed in a time scale which is small compared to a Hubble time. These include spirals, bars, bridges, tails, rings, thick discs and bulges. In some cases interactions may lead to mergings. We briefly review comparisons of the properties of merger remnants with those of elliptical galaxies, both for the case of pairwise mergings and the case of multiple mergings. Comment: 10 pages, no figures, review paper for the Euroconference II on Evolution of Galaxies at Reunion, Kluwer academic press, eds. M. Sauvage et al
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    ABSTRACT: In this series of papers we investigate the orbital structure of 3D models representing barred galaxies. In the present introductory paper we use a fiducial case to describe all families of periodic orbits that may play a role in the morphology of three-dimensional bars. We show that, in a 3D bar, the backbone of the orbital structure is not just the x1 family, as in 2D models, but a tree of 2D and 3D families bifurcating from x1. Besides the main tree we have also found another group of families of lesser importance around the radial 3:1 resonance. The families of this group bifurcate from x1 and influence the dynamics of the system only locally. We also find that 3D orbits elongated along the bar minor axis can be formed by bifurcations of the planar x2 family. They can support 3D bar-like structures along the minor axis of the main bar. Banana-like orbits around the stable Lagrangian points build a forest of 2D and 3D families as well. The importance of the 3D x1-tree families at the outer parts of the bar depends critically on whether they are introduced in the system as bifurcations in $z$ or in $\dot{z}$. Comment: 16 pages, 22 figures, 3 tables, to appear in MNRAS
    Monthly Notices of the Royal Astronomical Society 07/2002; DOI:10.1046/j.1365-8711.2002.05468.x · 5.11 Impact Factor
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