Document 
-
Articles citing this article
- Same authors
-
Related articles
- Recommend this article
- Download citation
- Alert me when this article is cited
- Alert me when this article is corrected
BibSonomy
CiteUlike
Connotea
Del.icio.us
Digg
Facebook
|
A&A 433, 1-13 (2005)
DOI: 10.1051/0004-6361:20041474
Thermal condensation in a turbulent atomic hydrogen flow
E. Audit1 and P. Hennebelle21 Service d'Astrophysique, CEA/DSM/DAPNIA/SAp, C. E. Saclay, 91191 Gif-sur-Yvette Cedex, France
e-mail: edouard.audit@cea.fr
2 Laboratoire de radioastronomie millimétrique, UMR 8112 du CNRS, École normale supérieure et Observatoire de Paris, 24 rue Lhomond, 75231 Paris Cedex 05, France
e-mail: patrick.hennebelle@ens.fr
(Received 15 June 2004 / Accepted 30 October 2004 )
Abstract
We present a numerical and analytical study of the thermal
fragmentation of a turbulent flow of interstellar hydrogen. We first
present the different dynamical processes and the large range of
spatial (and temporal) scales that need to be adequately represented
in numerical simulations. Next, we present bidimensional simulations
of turbulent converging flows which induce the dynamical condensation
of the warm neutral phase into the cold phase. We then analyse the
cold structures and the fraction of unstable gas in each simulation,
paying particular attention to the influence of the degree of
turbulence. When the flow is very turbulent a large fraction of the
gas remains in the thermally unstable domain. This unstable gas forms
a filamentary network. We show that the fraction of thermally
unstable gas is strongly correlated with the level of turbulence of
the flow. We then develop a semi-analytical model to explain the
origin of this unstable gas. This simple model is able to
quantitatively reproduce the fraction of unstable gas observed in the
simulations and its correlation with turbulence. Finally, we stress
the fact that even when the flow is very turbulent and in spite of the
fact that a large fraction of the gas is maintained dynamically in the
thermally unstable domain, the classical picture of a 2-phase medium
with stiff thermal fronts and local pressure equilibrium turns out to
be still relevant in the vicinity of the cold structures.
Key words: hydrodynamics -- instabilities -- ISM: kinematics and dynamics -- ISM: structure -- ISM: clouds
© ESO 2005
| What is OpenURL? |
