Issue |
A&A
Volume 404, Number 1, June II 2003
|
|
---|---|---|
Page(s) | 21 - 34 | |
Section | Astrophysical processes | |
DOI | https://doi.org/10.1051/0004-6361:20030436 | |
Published online | 26 May 2003 |
Turbulent viscosity in clumpy accretion disks
II. Supernova driven turbulence in the Galaxy
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
Corresponding author: B. Vollmer, bvollmer@mpifr-bonn.mpg.de
Received:
17
July
2002
Accepted:
18
March
2003
An analytical model for a turbulent clumpy gas disk is presented where
turbulence is maintained by the energy input due to supernovae.
Expressions for the disk parameters, global filling factors,
molecular fractions, and star formation rates are given as functions
of the Toomre parameter Q, the ratio between the cloud size
and the turbulent driving length scale δ,
the mass accretion rate within the disk ,
the constant of molecule formation α,
the disk radius, the angular velocity, and its radial derivative.
Two different cases are investigated: a dominating stellar disk and
a self-gravitating gas disk in z direction.
The turbulent driving wavelength is determined in a first
approach by energy flux conservation, i.e. the supernovae energy input
is transported by turbulence to smaller scales where it is dissipated.
The results are compared to those of a fully gravitational model.
For
and
both models are consistent with each other.
In a second approach the driving length scale is directly determined by the
size of supernovae remnants. Both models are applied to the Galaxy
and can reproduce its integrated and local gas properties.
The influence of thermal and magnetic pressure on the disk structure
is investigated. We infer
and
–0.1
yr-1 for the Galaxy.
Key words: ISM: clouds / ISM: structure / Galaxy: structure / galaxies: ISM
© ESO, 2003
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