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D.C.C. Yen, C. Yuan (Institute of Astronomy & Astrophysics, Academia Sinica, Taiwan, ROC)
It is well known that spiral density waves can be generated by a rotating bar through a resonance excitation mechanism. Associated with these waves is the angular momentum transport between the bar and the disk. As waves attenuated by viscosity, the angular momentum will be deposited in the disk. This will cause the disk matter moving inward or outward, depending respectively on whether the angular momentum carried by the waves is negative or positive. The re-distribution of the matter of this kind is especially important for the central gaseous disk, since it provides a mechanism of fueling AGN and starburst ring activities. The morphology and dynamics of a resonantly excited disk can be calculated analytically by non-linear asymptotic methods in a steady state limit. However, the evolution of the disk cannot be achieved unless we solve the full non-linear equations in time. For that, we must use numerical gasdynamics. In this report, we calculate three cases for the evolution of a central gas-dust disk with the relaxation code we develop. Spiral waves are generated by a bar (1) at the outer Lindblad resonance (OLR), (2) at the inner Lindblad resonance (ILR), and (3) both OLR and ILR are present. We wiill show in three short movies how the disk morphology changes in time for the above cases and discuss the relevance to the AGN and starburst ring activities in the center. The work is supported by NSC Grant 90-2112-M-001-052.