NOAO >   Observing Info >   Approved Programs >   2004A-0177

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Proposal Information for 2004A-0177


PI: Patrick Treuthardt, University of Alabama, treut001@bama.ua.edu
Address: Physics Department, Box 870324, Tuscaloosa, AL 35487, U.S.A.

CoI: Ronald J. Buta, University of Alabama
CoI: Heikki Salo, University of Oulu

Title: A Dynamical Study of Resonances in Barred Spiral Galaxies

Abstract: Dynamical orbit resonances constitute one of the most important factors governing the morphology and evolution of a barred disk galaxy. These resonances are tied to the pattern speed (\Omega_p) of the bar, an important unknown that defines the equilibrium structure of a galactic disk and which has not been measured for any significant number of galaxies. We propose to focus a dynamical study on a sample of early- to-intermediate Hubble type barred spiral galaxies where orbit resonances appear in the form of ring-like patterns of star formation. One of our goals is to directly measure \Omega_p in these galaxies using the well-known Tremaine-Weinberg (TW) method and then use dynamical simulations, in conjunction with near-IR images and 2-D velocity fields, to judge \Omega_p independent of the TW method. Our second goal is to measure and model rotation curves of a small set of SB(r) galaxies having similar bar strengths but very different inner ring shapes in order to determine the relative importance of the dark halo. This will help determine why recent observations contradict theory and indicate that inner ring shape is independent of bar strength. Our study has an advantage over past studies of barred spirals in that we focus on galaxies having well-defined morphological and kinematic constraints on \Omega_p. Some previous uses of the TW method focussed on SB0 galaxies which lack any independent \Omega_p constraints. Our analysis of SB(r) galaxies will be the first significant attempt to use planar resonance rings to probe dark matter halos.


National Optical Astronomy Observatory, 950 North Cherry Avenue, P.O. Box 26732, Tucson, Arizona 85726, Phone: (520) 318-8000, Fax: (520) 318-8360



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