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The Rate of Angular Momentum Loss from Cloud Cores

Published online by Cambridge University Press:  19 July 2016

Takenori Nakano*
Affiliation:
Department of Physics, Kyoto University Sakyo-ku, Kyoto 606, Japan

Extract

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The angular momentum is one of the major obstacles to the contraction of interstellar clouds. An efficient process of removing the angular momentum from the cloud is via transport along the magnetic field lines to the ambient medium. When the magnetic field is nearly uniform and the direction of the field lines is parallel to the rotation axis, the spin-down time of the cloud is given by σ/2ρVA, where σ is the column density of the cloud along the field lines, and ρ and VA are the density and the Alfvén velocity, respectively, in the ambient medium (Ebert et al. 1960; Mouschovias & Paleologou 1980). However, this is for a cloud with weak gravity. Because a cloud with strong gravity has contracted dragging the field lines, the ambient field is considerably distorted from uniformity. The spin-down time of such a cloud is shorter than given above (Gillis, Mestel & Paris 1974, 1979).

Type
6. Magnetic Fields in Molecular Clouds, Dark Globules and in the Pre-Stellar and Circumstellar Environment
Copyright
Copyright © Kluwer 1990 

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