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Steady‐state field‐aligned currents at Mercury
Author(s) -
Anderson Brian J.,
Johnson Catherine L.,
Korth Haje,
Slavin James A.,
Winslow Reka M.,
Phillips Roger J.,
McNutt Ralph L.,
Solomon Sean C.
Publication year - 2014
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 - 10.1002/2014gl061677
Subject(s) - geophysics , physics , magnetic field , magnetopause , dusk , electric field , current density , current (fluid) , planet , conductance , atmospheric sciences , magnetosphere , geology , astrophysics , astronomy , condensed matter physics , quantum mechanics , thermodynamics
Magnetic field observations acquired in orbit about Mercury by the MESSENGER spacecraft demonstrate the presence in the planet's northern hemisphere of Birkeland currents that flow to low altitudes. Currents of density 10–30 nA/m 2 flow downward at dawn and upward at dusk. Total currents are typically 20–40 kA and exceed 200 kA during disturbed conditions. The current density and total current are two orders of magnitude lower than at Earth. An electric potential of ~30 kV from dayside magnetopause magnetic reconnection implies a net electrical conductance of ~1 S. A spherical‐shell conductance model indicates closure of current radially through the low‐conductivity layers near the surface and by lateral flow from dawn to dusk through more conductive material at depth.