Issue |
A&A
Volume 367, Number 1, February III 2001
|
|
---|---|---|
Page(s) | 72 - 85 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20000425 | |
Published online | 15 February 2001 |
A cloudy model for the Circumnuclear Disk in the Galactic Centre
1
Institut für Theoretische Astrophysik der Universität Heidelberg, Tiergartenstraße 15, 69121 Heidelberg, Germany
2
Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
3
Observatoire de Meudon, DAEC, UMR 8631, CNRS et Université Paris 7, 92195 Meudon Cedex, France
Corresponding author: B. Vollmer, bvollmer@mpifr-bonn.mpg.de
Received:
23
July
1999
Accepted:
30
November
2000
We present a first attempt to construct an analytic model for a clumped
gas and dust disk and apply it to the Galactic Centre. The clumps
are described as isothermal spheres partially ionized by the external
UV radiation field. The disk structure formed by the clouds is described
as a quasi standard continuous accretion disk using adequately averaged
parameters of the discrete cloud model.
The viscosity in the Circumnuclear Disk is due to partially inelastic
cloud-cloud collisions. We find two different solutions for the set of equations
corresponding to two stable cloud regimes: (i) the observed molecular clouds and
(ii) much lighter and smaller clouds which correspond to the stripped cores of
the observed clouds.
It is shown that the resulting physical characteristics of the heavy clouds
and the disk are in very good agreement with all comparable observations
at multiple wavelengths. A mass accretion rate of
yr-1 for the isolated Circumnuclear Disk
is inferred. We propose that the Circumnuclear Disk has a much
longer lifetime (∼107 yr) than previously assumed.
Key words: ISM: clouds / ISM: evolution / ISM: HII region / Galaxy: center
© ESO, 2001
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