Journal Article

The approach to collapse of molecular clouds

Steven W. Stahler and Jeffrey J. Yen

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 396, issue 1, pages 579-588
Published in print June 2009 | ISSN: 0035-8711
Published online June 2009 | e-ISSN: 1365-2966 | DOI:
The approach to collapse of molecular clouds

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The dense molecular cloud cores that form stars, like other self-gravitating objects, undergo bulk oscillations. Just at the point of gravitational instability, their fundamental oscillation mode has zero frequency. We study, using perturbation theory, the evolution of a spherical cloud that possesses such a frozen mode. We find that the cloud undergoes a prolonged epoch of subsonic, accelerating contraction. This slow contraction occurs whether the cloud is initially inflated or compressed by the oscillation. The subsonic motion described here could underlie the spectral infall signature observed in many starless dense cores.

Keywords: stars: formation; ISM: clouds; ISM: kinematics and dynamics

Journal Article.  6640 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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