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Statistical Properties of Sub‐Ion Magnetic Holes in the Solar Wind at 1 AU
Author(s) -
Wang G. Q.,
Zhang T. L.,
Xiao S. D.,
Wu M. Y.,
Wang G.,
Liu L. J.,
Chen Y. Q.,
Volwerk M.
Publication year - 2020
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1029/2020ja028320
Subject(s) - solar wind , magnetosheath , physics , magnetic field , gyroradius , electron , pitch angle , magnetic reconnection , magnetopause , computational physics , geophysics , quantum mechanics
Sub‐ion magnetic holes are rich in the terrestrial plasma sheet and magnetosheath. Here, we statistically investigate 60 sub‐ion magnetic holes in the solar wind at 1 AU using the high‐resolution data measured by the Magnetospheric Multiscale mission. We find that they are observed with a duration of 0.1 –0.5 s, and the lengths of their cross‐section are ~0.1 –0.6 ion gyroradius. These structures prefer to occur in the slow solar wind with a weak ambient magnetic field strength. They also prefer to occur in the marginally mirror stable or unstable environments. Electron vortices as well as an enhancement of the electron perpendicular temperature and electron fluxes at ~90° pitch angle tend to be observed inside some magnetic holes with a large ambient magnetic field strength. By contrast, there are no clearly observational electron vortices as well as the electron fluxes at ~90° pitch angle inside some magnetic holes with a weak ambient magnetic strength. The current density with a value of ~10 –50 nA/m 2 reveals that the corresponding maximum electron velocity is <10 km/s inside some magnetic holes, lower than the level of the observational electron velocity noise, which prevents the detection of the weak electron vortex. We suggest that electron vortices exist inside all the sub‐ion magnetic holes in the solar wind. The generation of these sub‐ion magnetic holes might be explained by the electron magnetohydrodynamics soliton and the electron vortex magnetic hole.