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Modelling the Structure of the Ringed Spiral NGC 4736

Published online by Cambridge University Press:  12 April 2016

Wim van Driel
Affiliation:
Nançay Radio Astronomy Observatory, Observatoire de Paris, France
Pieter Mulder
Affiliation:
Kapteyn Astronomical Institute, Groningen University, The Netherlands
Françoise Combes
Affiliation:
DEMIRM, Observatoire de Paris, France

Abstract

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We studied the ringed RSab(r)-type spiral NGC 4736, which has a probably slightly oval disk and a very small bar. We mapped the galaxy in the HI and Hα spectral lines and we obtained long-slit optical spectra. These data were modeled using a 2-D gas dynamical code. The 2-D potential used is axisymmetric in the inner and outer regions and oval (b/a=0.8) at intermediate radii only. The oval component rotates at a pattern speed of 40 km s–1 kpc–1, close to the observed value. Inner and outer rings, like those observed, form at the inner and outer Lindblad resonances, though they co-exist only during a limited time interval in the simulations. The morphology and kinematics of the inner ring and spiral structure as observed in neutral and ionized hydrogen can be well understood in terms of gas dynamical simulations, given the form of the (stellar) potential. What remains to be explained is the origin of the nonaxisymmetric features in the mass distribution defining the potential.

Type
Posters for Part III and Part IV
Copyright
Copyright © Astronomical Society of the Pacific 1996

References

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