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Evidence of Magnetic Nulls in the Reconnection at Bow Shock
Author(s) -
Chen Z. Z.,
Fu H. S.,
Wang Z.,
Liu C. M.,
Xu Y.
Publication year - 2019
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2019gl084360
Subject(s) - magnetosheath , magnetic reconnection , physics , magnetopause , bow shock (aerodynamics) , geophysics , astrophysics , foreshock , magnetosphere , solar wind , spacecraft , magnetic field , shock wave , astronomy , mechanics , seismology , geology , aftershock , quantum mechanics
Abstract Magnetic nulls are believed to play important roles in the energy dissipation during reconnection. Such nulls have been observed in reconnection at the magnetopause, magnetosheath, and magnetotail but have never been observed in reconnection at the bow shock. Recently, four reconnection events were reported at the terrestrial bow shock, by utilizing Magnetospheric Multiscale (MMS) data. We examine whether the magnetic nulls exist in these events. We successfully find radial nulls in three of the events, meaning that spacecraft were close to X points in these events; we, however, cannot find radial nulls in another event, which was actually a crossing of the reconnection exhaust region. The minimum distance between radial nulls and spacecraft is 8 km, about 0.3 ion inertial length. We reconstruct topologies of these nulls and subsequently resolve the reconnection rates in these events. We find that the resolved reconnection rates are comparable with those at the magnetopause and magnetotail. Surprisingly, we do not find electron heating at the radial nulls. Our results are useful to understand the reconnection at bow shock.