Dissipation of turbulence by magnetohydrodynamic shock waves

Andrew Lehmann*, Mark Wardle

*Corresponding author for this work

    Research output: Contribution to journalConference paperpeer-review


    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.

    Original languageEnglish
    Article numberE48
    Pages (from-to)1-2
    Number of pages2
    JournalProceedings of the International Astronomical Union
    Issue number315
    Publication statusPublished - 2016
    Event315th Symposium of the International Astronomical Union - Honolulu, United States
    Duration: 3 Aug 20157 Aug 2015


    • (magnetohydrodynamics:) MHD
    • shock waves
    • ISM: clouds
    • ISM: molecules


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