Journal Article

Dynamical stability and evolution of the discs of Sc galaxies

B. Fuchs and S. Von Linden

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 294, issue 4, pages 513-522
Published in print March 1998 | ISSN: 0035-8711
Published online March 1998 | e-ISSN: 1365-2966 | DOI:
Dynamical stability and evolution of the discs of Sc galaxies

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We examine the local stability of galactic discs against axisymmetric density perturbations with special attention to the different dynamics of the stellar and gaseous components. In particular, the discs of the Milky Way and of NGC 6946 are studied. The Milky Way is shown to be stable, whereas the inner parts of NGC 6946, a typical Sc galaxy from the Kennicutt sample, are dynamically unstable. The ensuing dynamical evolution of the composite disc is studied by numerical simulations. The evolution is so fierce that the stellar disc heats up dynamically on a short time-scale to such a high degree, which seems to contradict the morphological appearance of the galaxy. The star formation rate required to cool the disc dynamically is estimated. Even if the star formation rate in NGC 6946 is at present high enough to meet this requirement, it is argued that the discs of Sc galaxies cannot sustain such a high star formation rate for extended periods.

Keywords: Galaxy: kinematics and dynamics; galaxies: evolution; galaxies: individual: NGC 6946; galaxies: kinematics and dynamics; galaxies: structure

Journal Article.  0 words. 

Subjects: Astronomy and Astrophysics

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