Free access article

A&A 438, 23-29 (2005)
DOI: 10.1051/0004-6361:20052972

Solitary waves in self-gravitating molecular clouds

T. Cattaert¹ and F. Verheest<sup>1, 2

1</sup>  Sterrenkundig Observatorium, Universiteit Gent, Krijgslaan 281, 9000 Gent, Belgium
    e-mail: Frank.Verheest@UGent.be
²  School of Physics (Howard College Campus), University of KwaZulu-Natal, Durban 4041, South Africa

(Received 2 March 2005 / Accepted 8 April 2005)

Abstract
Molecular clouds are self-gravitating fluids that support different waves and contain highly nonlinear clumps and filaments, for which explanations have been sought in terms of solitons. The present paper explores the possibility that several (neutral) species with different thermal speeds coexist, as in a molecular cloud consisting of gas and dust, or of a mixture of normal matter and dark matter. It is shown that this model can support soliton formation, both with humps or dips in the self-gravitational potential. The existence domain has been given in terms of the hot species Mach number and fractional mass density, in a gas-dynamic description which emphasizes the constraints coming from the sonic and neutral points, and from the limits due to infinite compression or total rarefaction. One species is compressed while the other is rarefied, allowing the system to reach a mass neutral point outside equilibrium. In this way, solitons are possible without invoking interaction with a weakly ionized cloud component or involving envelope solitons that are not really stationary structures.

Key words: gravitation -- hydrodynamics -- ISM: clouds -- waves

© ESO 2005

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

• If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
• You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
• You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.