Hydrodynamical Simulations of the Barred Spiral Galaxy NGC 6782
Abstract
NGC 6782 is a type (R1R2’)SB(r)a galaxy with multiple ring patterns. It has a nearly circular bright nuclear ring connected with a pair of almost straight dust lanes, the other ends of which attach to a diamond-shaped (or pointy oval) inner ring. Two faint arms in turn extend from the two tips of the inner ring to the outermost parts of the galaxy, forming a faint double outer ring-pseudoring morphology. In this study we use numerical simulations to show that such striking features can be reproduced by imposing a strong bar to a gaseous disk system. Since strong bar potentials may, through instabilities, lead to chaotic sub-structures, they present challenging problems to the numerical simulations. Our simulations are performed with our own Antares code, which employs Cartesian coordinates and the higher-order Godunov scheme with unsplit flux calculated from the exact Riemann solver. Calculations are carried out with and without self-gravitation, which produce similar results. In both cases, the bar is able to drive spiral density waves simultaneously at both the outer Lindblad resonance (OLR) and the inner Lindblad resonance (ILR). When the bar potential is strong enough, these two waves excited at the two resonances interact with each other, giving rise to the diamond-shaped structure. All the essential features are in excellent agreement with observations. Our work is in part supported by National Science Council, Taiwan, NSC95-2752-M-001-009-PAE, and by NSF grant AST050-7140.
- Publication:
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American Astronomical Society Meeting Abstracts
- Pub Date:
- December 2006
- Bibcode:
- 2006AAS...209.0408L