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Astron. Astrophys. 324, L21-L24 (1997)


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Letter to the Editor

Inhibition of turbulent transfer in self-gravitating flows below the Jeans length

R. Grappin J. Léorat S. Hulin

DAEC, Observatoire de Paris, Université Paris VII, CNRS (UA 173), F- 92195 Meudon Cedex, France and ASCI, France

Received 23 January 1997 / Accepted 22 April 1997

Abstract

Turbulent flows within clouds with Jeans numbers of order unity are observed in the interstellar medium. In the absence of self-gravitation, compressible turbulent flows steepen, form shocks, and hence dissipate rapidly. We show here that, for wavelengths immediately below the gravitational instability threshold, this nonlinear steepening does not occur, and dissipation is drastically reduced. This result might alleviate somewhat the problem of feeding the turbulence in marginally stable clouds (with Jeans number slightly below unity).

Key words: Gravitation – Hydrodynamics – Turbulence – Interstellar matter: kinematics and dynamics – Methods: numerical

Send offprint requests to: R. Grappin; Observatoire de Paris, F-92195 Meudon Cedex, France

© European Southern Observatory (ESO) 1997

Online publication: May 26, 1998

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