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Galactic
Dynamics
Chi
Yuan and his research group focused on the structure and evolution
of the inner gas-dust disk of nearby spiral galaxies in 2002.
They extended the non-linear asymptotic theory developed earlier
by their group and successfully demonstrated that the observed
spiral structure and its kinematics of NGC5248 can be explained
by the theory (Yang 2002). Furthermore they showed that the
rigid-body rotation near the center forms an exceedingly firm
evanescence region which waves cannot penetrate and hence makes
it difficult to fuel AGN and starburst ring activities in the
center. However, slightly deviating from rigid-body rotation
would allow waves to go to the center (Yuan, Lin and Chen 2002;
Yuan and Chen 2002; Chen 2002). Along the theoretical development,
Yuan wrote a review article of the subject published in Space
Science Review (Yuan 2002). For the evolution of the central
gas-dust disks, the group has developed high-performance gas-dynamic
codes, in particular for solving bar-driven density waves in
galactic disks (see description in the CFD section). The codes
are written in both the relaxation method and the high-order
Godunov method. For the stellar dynamics of disk galaxies, Yuan's
collaboration with Uri Griv still continues (Griv, Gadelin and
Yuan 2002a and 2002b).
Figure
4.: Numerical simulations of NGC5248. The sequence from left
to right and top to bottom shows the evolution of the gas
disk of NGC5248 under the influence of a major bar in the
system. (with David C.C. Yen)
All
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