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The formation of C-shocks: Structure and signatures

Smith, M.D., Low, M.-M.M. (1997) The formation of C-shocks: Structure and signatures. Astronomy and Astrophysics, 326 (2). pp. 801-810. ISSN 0004-6361. (The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided) (KAR id:50149)

The full text of this publication is not currently available from this repository. You may be able to access a copy if URLs are provided.
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Shock waves in molecular clouds should evolve into continuous or C-type structures due to the magnetic field and ion-neutral friction. We here determine whether and how this is achieved through plane-parallel numerical simulations using an extended version of ZEUS. We first describe and test the adapted code against analytical results, laying the necessary foundations for subsequent works on supersonic ambipolar diffusion, including C-type jets and shock instability. The evolution away from jump shocks toward the numerous steady C-shock sub-types is then investigated. The evolution passes through four stages, which possess distinctive observational properties. The time scales and length scales cover broad ranges. Specific results are included for shock types including switch, absorber, neutralised, oblique, transverse and intermediate. Only intermediate Type II shocks and 'slow shocks', including switch-off shocks, remain as J-type under the low ion levels assumed. Other shocks transform via a steadily growing neutral precursor to a diminishing jump. For neutralised shocks, this takes the form of an extended long-lived ramp. Molecular hydrogen emission signatures are presented. After the jump speed has dropped to under 25kms-1, a nondissociative jump section can dominate the spectra for a long period. This produces a high-excitation spectrum. Once the jump has further weakened, to < 8 kms-1, the fully developed ion front is responsible for brisk progress towards a constant C-type excitation. The time scale for emission-line variations is ? (6/ni) yr, where ni, is the pre-shock ion number density.

Item Type: Article
Uncontrolled keywords: ISM: clouds, ISM: jets and outflows, ISM: kinematics and dynamics, ISM: lines and bands, MHD, Shock waves
Subjects: Q Science > QB Astronomy > QB460 Astrophysics
Divisions: Divisions > Division of Natural Sciences > Physics and Astronomy
Depositing User: Giles Tarver
Date Deposited: 11 Aug 2015 10:29 UTC
Last Modified: 16 Nov 2021 10:20 UTC
Resource URI: (The current URI for this page, for reference purposes)

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