Supermagnetosonic jets behind a collisionless quasi-parallel shock

H. Hietala; T. V. Laitinen; K. Andréeová; R. Vainio; A. Vaivads; M. Palmroth; T. I. Pulkkinen; H. E. J. Koskinen; E. A. Lucek; H. Rème

doi:10.1103/physrevlett.103.245001

arXiv · 0911.1687

Supermagnetosonic jets behind a collisionless quasi-parallel shock

H. Hietala·T. V. Laitinen·K. Andréeová·R. Vainio·A. Vaivads·M. Palmroth·T. I. Pulkkinen·H. E. J. Koskinen·E. A. Lucek·H. Rème

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Abstract

The downstream region of a collisionless quasi-parallel shock is structured containing bulk flows with high kinetic energy density from a previously unidentified source. We present Cluster multi-spacecraft measurements of this type of supermagnetosonic jet as well as of a weak secondary shock front within the sheath, that allow us to propose the following generation mechanism for the jets: The local curvature variations inherent to quasi-parallel shocks can create fast, deflected jets accompanied by density variations in the downstream region. If the speed of the jet is super(magneto)sonic in the reference frame of the obstacle, a second shock front forms in the sheath closer to the obstacle. Our results can be applied to collisionless quasi-parallel shocks in many plasma environments.

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H. Hietala, T. V. Laitinen, K. Andréeová, R. Vainio, A. Vaivads, M. Palmroth, T. I. Pulkkinen, H. E. J. Koskinen, E. A. Lucek, H. Rème. 2009-11-09. Supermagnetosonic jets behind a collisionless quasi-parallel shock. https://doi.org/10.1103/physrevlett.103.245001

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