Ultra-low frequency waves in the ion foreshock of Mercury: A global hybrid modeling study

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We study the solar wind interaction with Mercury using a global three-dimensional hybrid model. In the analysed simulation run, we find a well-developed, dynamic Hermean ion foreshock ahead of the quasi-parallel bow shock under upstream solar wind and interplanetary magnetic field (IMF) conditions corresponding to the orbital perihelion of the planet. A portion of the incident solar wind ion flux is scattered back upstream near the quasi-parallel bow shock including both major solar wind ion species, protons and alphas. The scattered particles form the Hermean suprathermal foreshock ion population. A significant part of the suprathermal population is backstreaming with a velocity component towards the Sun in the near-foreshock at the planetocentric distance of few planetary radii in the plane of the IMF. The ion foreshock is associated with large-scale, oblique fast magnetosonic waves in the ultra-low-frequency (ULF) range convecting downstream with the solar wind. The ULF wave period is about 5 s in the analysed upstream condition case at Mercury, which corresponds to the 30-s foreshock waves at Earth when scaled by the IMF magnitude.
Original languageEnglish
Pages (from-to)4147-4161
JournalMonthly Notices of the Royal Astronomical Society
Issue number3
Publication statusPublished - Jan 2020
MoE publication typeA1 Journal article-refereed


  • magnetic fields
  • plasmas
  • waves
  • solar wind
  • planet-star interactions

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    Shocks and Magnetosheaths in the Heliosphere

    Alho, M., Järvinen, R., Lakka, A., Pulkkinen, T. & Knuuttila, O.


    Project: Academy of Finland: Other research funding

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