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arXiv · 1903.07774

Bow shocks, bow waves, and dust waves. II. Beyond the rip point

William J. Henney·S. J. Arthur
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Abstract

Dust waves are a result of gas-grain decoupling in a stream of dusty plasma that flows past a luminous star. The radiation field is sufficiently strong to overcome the collisional coupling between grains and gas at a "rip-point", where the ratio of radiation pressure to gas pressure exceeds a critical value of roughly 1000. When the rip point occurs outside the hydrodynamic bow shock, a separate dust wave may form, decoupled from the gas shell, which can either be drag-confined or inertia-confined, depending on the stream density and relative velocity. In the drag-confined case, there is a minimum stream velocity of roughly 60 km/s that allows a steady-state stagnant drift solution for the dust wave apex. For lower relative velocities, the dust dynamics close to the axis exhibit a limit cycle behavior (rip and snap back) between two different radii. Strong coupling of charged grains to the plasma's magnetic field can modify these effects, but for a quasi-parallel field orientation the results are qualitatively similar to the non-magnetic case. For a quasi-perpendicular field, on the other hand, the formation of a decoupled dust wave is strongly suppressed.

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William J. Henney, S. J. Arthur. 2019-04-11. Bow shocks, bow waves, and dust waves. II. Beyond the rip point. https://doi.org/10.1093/mnras%2Fstz1130

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