A1 Refereed original research article in a scientific journal
Candidates for downstream jets at interplanetary shocks
Authors: Hietala, H.; Trotta, D.; Fedeli, A; Wilson III, L. B.; Vuorinen, L.; Coburn, J. T.
Publisher: Oxford University Press
Publication year: 2024
Journal: Monthly Notices of the Royal Astronomical Society
Volume: 531
Issue: 2
First page : 2415
Last page: 2421
eISSN: 1365-2966
DOI: https://doi.org/10.1093/mnras/stae1294
Web address : https://doi.org/10.1093/mnras/stae1294
Self-archived copy’s web address: https://research.utu.fi/converis/portal/detail/Publication/456793037
Localized dynamic pressure enhancements arising from kinetic processes are frequently observed downstream of the Earth’s bow shock. These structures, called jets, modify their plasma surroundings and participate in particle energization. Here, we report the first observations of jet-like structures in a non-planetary shock environment: downstream of interplanetary shocks. We introduce an analysis approach suitable for such conditions and apply it to Wind spacecraft data. We present one event with a Mach number similar to the Earth’s bow shock as a benchmark, as well as two low Mach number, low beta shocks: a parameter range that is difficult to access at planets. The jet-like structures we find are tens of ion inertial lengths in size, and some are observed further away from the shock than in a limited magnetosheath. We find that their properties are similar to those of magnetosheath jets: in the frame of the shock these structures are fast, cold, and most have no strong magnetic field variations. All three interplanetary shocks feature foreshock activity, but no strongly compressive waves. We discuss the implications, these findings have for the proposed jet formation mechanisms.
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Funding information in the publication:
The work of HH is supported by the Royal Society award URF\R1\180671. HH thanks discussions at the International Space Science Institute (ISSI) in Bern, through ISSI International Team project #465 (Foreshocks Across The Heliosphere: System Specific or Universal Physical Processes?). The work of DT is supported from the European Union’s Horizon 2020 research and innovation programme under grant agreement No. 101004159 (SERPENTINE, www.serpentine-h2020.eu). Some of the work was supported by the Geospace Environment Modeling Focus Group ‘Particle Heating and Thermalization in Collisionless Shocks in the Magnetospheric multiscale mission (MMS) Era’ led by L. B. Wilson III. LV acknowledges the financial support of the University of Turku Graduate School.
