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

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Journal Title
Journal ISSN
Volume Title
A1 Alkuperäisartikkeli tieteellisessä aikakauslehdessä
Date
2020-01-01
Major/Subject
Mcode
Degree programme
Language
en
Pages
4147-4161
Series
Monthly Notices of the Royal Astronomical Society, Volume 491, issue 3
Abstract
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.
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Keywords
magnetic fields, plasmas, waves, solar wind, planet-star interactions
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Citation
Järvinen , R , Alho , M , Kallio , E & Pulkkinen , T 2020 , ' Ultra-low frequency waves in the ion foreshock of Mercury: A global hybrid modeling study ' , Monthly Notices of the Royal Astronomical Society , vol. 491 , no. 3 , pp. 4147-4161 . https://doi.org/10.1093/mnras/stz3257