AAS 205th Meeting, 9-13 January 2005
Session 60 Secular Evolution Potpourri: Star Formation to Galactic Structures
Poster, Tuesday, January 11, 2005, 9:20am-6:30pm, Exhibit Hall

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[60.12] The Formation of Starburst Ring, Circumnuclear Molecular Disk, and Diamond-shape Structures in Disk Galaxies

D.C. Yen (Dept. of Mathematics, Fu-Jen Catholic U., Taiwan, R.O.C), C. Yuan (IAA, Academia Sinica, Taiwan, R.O.C.)

Starburst rings are one of most spectacular phenomena observed in the center of many nearby galaxies. Recent high resolution observations have revealed that star burst rings are often composed of two tightly wound spirals. Density wave theory successfully shows that tightly wound spirals can be excited resonantly by a rotating bar potential. We will use numerical simulations to demonstrate the formation of starburst rings. In addition, we will show for certain galaxies with rapidly rising rotation curves, a tiny disk of extremely gas high density near the center can be formed as well. This disk, with weak star formation activities, is in close resemblance to the dense circumnuclear molecular disks seen in the center of many nearby galaxies, which may or may not have AGN in the nucleus. The simulations to be presented here are using the high order Godunov method featured with exact Riemann solver and fft Poisson solver. The simulations use Milky Way's rotation curve to demonstrate the formation of starburt rings and the dense circumnuclear molecular disk near the center. On the other hand, simulations using a nearly-flat rotation curve further result in a diamond-shape structure in addition to starburt rings and the dense circumnuclear molecular disk. Such results are relevant to galaxy NGC6782, in which a diamond-shaped ring is observed and with the central ring, forms the famous double-ring structure.

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© 2004. The American Astronomical Society.