EDP Sciences
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Volume 382, Number 3, February II 2002
Page(s) 872 - 887
Section Galactic structure and dynamics
DOI http://dx.doi.org/10.1051/0004-6361:20011640

A&A 382, 872-887 (2002)
DOI: 10.1051/0004-6361:20011640

Turbulent viscosity in clumpy accretion disks

Application to the Galaxy
B. Vollmer and T. Beckert

Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany

(Received 29 May 2001/ Accepted 16 November 2001 )

The equilibrium state of a turbulent clumpy gas disk is analytically investigated. The disk consists of distinct self-gravitating clouds. Gravitational cloud-cloud interactions transfer energy over spatial scales and produce a viscosity, which allows mass accretion in the gas disk. Turbulence is assumed to be generated by instabilities involving self-gravitation and to be maintained by the energy input from differential rotation and mass transfer. Disk parameters, global filling factors, molecular fractions, and star formation rates are derived. The application of our model to the Galaxy shows good agreement with observations. They are consistent with the scenario where turbulence generated and maintained by gravitation can account for the viscosity in the gas disk of spiral galaxies. The rôle of the galaxy mass for the morphological classification of spiral galaxies is investigated.

Key words: ISM: clouds -- ISM: structure -- Galaxy: structure -- galaxies: ISM

Offprint request: B. Vollmer, bvollmer@mpifr-bonn.mpg.de

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