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2. The spiral-vortex structure of flat galaxies (prediction, theory, laboratoy and numerical experiments, observations)

Creator:
Afanasiev, V. L., P. V., Fridman, A. M., Ivchenko, I. N., Makov, Tu. N., Morozov, A. G., Nezlin, M. V., Pasha, I. I., Polyschenko, V. L., Rylov, A. Yu., Snezhkin, E. N., Torgashin, Yu. V., Trubnikov, A. S., and Zasov, A. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space research, flat galaxies, and spiral-vortex structures
Language:
Czech
Description:
Recent observations show a dip on the rotation curve for most of spiral galaxies,Theoretically, it implies that spiral density waves must be induced by shear instabilities,Calculations prove that the observed amount of gas In galactic disks (10% for the Galaxy) is sufficient to develop the hydrodynamical Instability in gas subsystems. As surface density perturbations of shallow water and galactic gas disks are described by the same equations, experiments with shallow water rotating slmilar to galactic disks have been made, In stationary stages of rotation stationary spiral pattems occur. The number of arms depends on the profile of rotation curve, in agreement with theoretical results, Different rotation parameters lead to different structures: the circular mode, one-, two-, ... , eight-armed spirals. Branching of the spirals is observed when rotation parameters change,which suggests that the spiral branching in several galaxies comes from their non-stationary rotation. Anticyclonic vortices are observed between the arms, Azimuthal averaging of the surface density, gives a good fit for the galaxy: minlmum of before the molecular ring, for realistic profiles of shallow water rotation the spirals are trailing, But they happen to lead for opposite directions of rotation of inner and outer regions, It may explain the leading spirals in galaxies whose spin is opposite either to that oft.blose companions or to the vector of orbital momentum of the pairs. Numerical computations confirm the theoretical and experimental results.They also show a formation like a "molecular ring". Preliminary observational data agree with these results.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public