Electronic Resource
Springer
Astrophysics and space science
233 (1995), S. 97-109
ISSN:
1572-946X
Source:
Springer Online Journal Archives 1860-2000
Topics:
Physics
Notes:
Abstract In a weakly ionized magnetized medium the dissipation in a shock moving at a speed sufficiently below the speed of high frequency hydromagnetic waves occurs on a lengthscale that is very large compared to any of the collision lengths. Chemistry affects the structures of these continuous or ‘C-type’ shocks which are sometimes unstable. In dark cloud shocks grain-neutral friction is an important dissipation process, and the adoption of a fluid description of grain dynamics elucidates various effects which include the onset of anE ×B drift-driven runaway in some perpendicular shocks. The imperfect nature of the conductivity in the clouds may cause significant rotation of the magnetic field about the shock propagation direction in a dense cloud shock. Models of shocks in which continuous dissipation is important have been developed in studies of the origins of CH+ in diffuse clouds, H2 emission features with widths of around 100 km s−1 in Orion and OH masers around young stars, but CH+ and such broad H2 features may arise in boundary layers between molecular regions and fast flows.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF00627338
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