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P. M. Treuthardt, R. J. Buta (U. of Alabama), H. Salo (U. of Oulu)
Resonances in disk galaxies play a fundamental role in galactic evolution because resonant stars may exchange angular momentum with a pertubation and thereby strengthen or weaken it (Athanassoula 2003, MNRAS, 341, 1179). In many disk galaxies, resonance regions are visible as distinct inner, outer, and nuclear rings of star formation. These rings act as tracers of the associated perturbation's pattern speed (\Omegap). One of two ways of estimating \Omegap is the direct Tremaine-Weinberg (1984, ApJ, 282, 5) method, which uses luminosity-weighted positions and velocities along strips parallel to the major axis. The second and more indirect way, is the numerical simulation method (e.g. Salo et al. 1999, AJ, 117, 778), which matches a cloud-particle model to the observed gas distribution and velocity field. This poster describes our project to use both methods on a small sample of ringed spiral galaxies in order to test the resonance idea of galactic rings (Buta and Combes 1996, Fund. Cos. Phys. 17, 95) and also to determine if the two methods give consistent results. Focusing a pattern speed study on resonance ring galaxies has the benefit of constraints, provided by the rings, on the parameters governing morphology. Our numerical analysis is based on near-infrared images which are used to infer galactic gravitational potentials.
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Bulletin of the American Astronomical Society, 37 #2
© 2005. The American Astronomical Soceity.