Journal Article

Stellar and gas dynamics of late-type barred-spiral galaxies: NGC 3359, a test case

P. A. Patsis, D. E. Kaufmann, S. T. Gottesman and V. Boonyasait

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 394, issue 1, pages 142-156
Published in print March 2009 | ISSN: 0035-8711
Published online March 2009 | e-ISSN: 1365-2966 | DOI: http://dx.doi.org/10.1111/j.1365-2966.2008.14335.x
Stellar and gas dynamics of late-type barred-spiral galaxies: NGC 3359, a test case

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We study the dynamics of a model for the late-type barred-spiral galaxy NGC 3359 by using both observational and numerical techniques. The results of our modelling are compared with photometric and kinematical data. The potential used is estimated directly from observations of the galaxy. It describes with a single potential function, a barred-spiral system with an extended spiral structure. Thus, the study of the dynamics in this potential has an interest by itself. We apply orbital theory and response models for the study of the stellar component, and smoothed particle hydrodynamics for modelling the gas. In particular, we examine the pattern speed of the system and the orbital character (chaotic or ordered) of the spiral arms. We conclude that the spiral pattern rotates slowly, in the sense that its corotation is close to or even beyond the end of the arms. Although a single, slow pattern speed could, under certain assumptions, characterize the whole disc, the comparison with the observational data indicates that probably the bar and the spirals have different angular velocities. In our two pattern speeds model, the best fit is obtained with a bar ending close to its 4:1 resonance and a more slowly rotating spiral. Assuming an 11 Mpc distance to the galaxy, a match of our models with the observed data indicates a pattern speed of about 39 km s−1 kpc−1 for the bar and about 15 km s−1 kpc−1 for the spiral. We do not find any indication for a chaotic character of the arms in this barred-spiral system. The flow in the region of the spirals can best be described as a regular ‘precessing-ellipses flow’.

Keywords: ISM: kinematics and dynamics; galaxies: kinematics and dynamics; galaxies: spiral; galaxies: structure

Journal Article.  11292 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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