On a general fluid dynamical theory of discrete unstable spiral modes in disk-shaped galaxies |
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| Authors: | Ronald F Pannatoni |
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| Institution: | Box 1152, Rt. 2, Franklin , North Carolina, 28734, U.S.A |
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| Abstract: | Abstract A general fluid dynamical theory of discrete unstable spiral modes in disk-shaped galaxies is described. This formulation of modes includes a radiation boundary condition and an exact numerical treatment of the Poisson equation. Thus, the modes are maintained by an outward transport of angular momentum, but they may be composed of both leading and trailing waves. A numerical scheme based on this formulation is described, and examples of modes obtained with this scheme are presented. These examples compare favorably with calculations based on the original asymptotic theory of Bertin, Lau, Lin and Mark. The implications of the present formulation of modes in galactic models support the hypothesis of a quasi-stationary spiral structure. |
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