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Dissipation of turbulence by magnetohydrodynamic shock waves

Part of: IAU Issue 315 - From Interstellar Clouds...

Published online by Cambridge University Press:  12 September 2016

Andrew Lehmann  and
Mark Wardle
Andrew Lehmann
Affiliation:
Department of Physics and Astronomy, and Research Centre in Astronomy, Astrophysics and Astrophotonics Macquarie University, 2109, NSW, Sydney email: [email protected]
Mark Wardle
Affiliation:
Department of Physics and Astronomy, and Research Centre in Astronomy, Astrophysics and Astrophotonics Macquarie University, 2109, NSW, Sydney email: [email protected]
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Abstract

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We characterise steady, one-dimensional fast and slow magnetohydrodynamic (MHD) shocks using a two-fluid model. Fast MHD shocks are magnetically driven, forcing ions to stream through the neutral gas ahead of the shock front. This magnetic precursor heats the gas sufficiently to create a large, warm transition zone where all fluid variables only weakly change in the shock front. In contrast, slow MHD shocks are driven by gas pressure where neutral species collide with ion species in a thin hot slab that closely resembles an ordinary gas dynamic shock.

We computed observational diagnostics for fast and slow shocks at velocities vs=2–4 km/s and preshock Hydrogen nuclei densities nH = 102-4 cm−3. We followed the abundances of molecules relevant for a simple oxygen chemistry and include cooling by CO, H2 and H2O. Estimates of intensities of 12CO rotational lines show that high-J lines, above J = 6 → 5, are more strongly excited in slow MHD shocks.

Keywords

(magnetohydrodynamics:) MHDshock wavesISM: cloudsISM: molecules
Type
Poster Papers
Information
Proceedings of the International Astronomical Union , Volume 11 , Symposium S315: From Interstellar Clouds to Star-Forming Galaxies: Universal Processes? , August 2015 , E48
Copyright
Copyright © International Astronomical Union 2016 

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