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The turbulent environment of low-mass dense cores

Published online by Cambridge University Press:  01 August 2006

E. Falgarone ,
P. Hily-Blant ,
J. Pety  and
G. Pineau des Forêts
E. Falgarone
Affiliation:
LERMA/LRA, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France email: edith@lra.ens.fr
P. Hily-Blant
Affiliation:
IRAM, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France email: hilyblan@iram.fr, pety@iram.fr
J. Pety
Affiliation:
LERMA/LRA, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France email: edith@lra.ens.fr IRAM, 300 rue de la Piscine, 38406 Saint Martin d'Hères, France email: hilyblan@iram.fr, pety@iram.fr
G. Pineau des Forêts
Affiliation:
LERMA/LRA, Ecole Normale Supérieure, 24 rue Lhomond, 75005 Paris, France email: edith@lra.ens.fr IAS, Université Paris-Sud, 91405 Orsay, France email: guillaume.pineaudesforets@ias.u-psud.fr
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Abstract

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The signatures of intermittent dissipation of turbulent energy have been sought in the translucent environment of a low-mass dense core. Molecular line observations reveal a network of narrow filamentary structures, found on statistical grounds to be the locus of the largest velocity shears. Three independent properties of these structures make them the plausible sites of intermittent dissipation of turbulence: (1) gas there is warmer and more diluted than average, (2) it bears the signatures of a non-equilibrium chemistry triggered by impulsive heating due to turbulence dissipation, and (3) the power that these structures radiate in the gas cooling lines (mostly H2) is so large that it balances the total energy injection rate of the turbulent cascade, for a volume filling factor of only a few percents, consistent with other observations in the Solar Neighborhood. These filamentary structures may act as tiny seeds of gas condensation in diffuse molecular gas. They do not exhibit the properties of steady-state low-velocity magneto-hydrodynamic (MHD) shocks, as presently modelled.

Keywords

TurbulenceastrochemistryMHDISM:evolutionISM:structureISM:moleculesISM:cloudstars:formationlines:profilesradio lines:ISM
Type
Contributed Papers
Information
Proceedings of the International Astronomical Union , Volume 2 , Symposium S237: Triggered Star Formation in a Turbulent ISM , August 2006 , pp. 24 - 30
Copyright
Copyright © International Astronomical Union 2007

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