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On the possible formation of Alfvén wings at Mercury during encounters with coronal mass ejections
Author(s) -
Sarantos Menelaos,
Slavin James A.
Publication year - 2009
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 - 10.1029/2008gl036747
Subject(s) - physics , solar wind , coronal mass ejection , interplanetary spaceflight , magnetosphere , mach number , magnetohydrodynamics , plasma , magnetic field , interplanetary magnetic field , helmet streamer , geophysics , astrophysics , mechanics , nuclear physics , quantum mechanics
The solar wind conditions near Mercury's perihelion, especially during Interplanetary Coronal Mass Ejection (ICME) events, will often be characterized by very low Alfvén Mach number (≤3). We suggest that the low Mach numbers and large north‐south magnetic fields during ICMEs will lead to the formation of “Alfvén wings” that will affect the configuration of the Hermean magnetosphere. It is shown that an electrical conductance threshold of about 5 S, comparable to the Alfvén conductance in the solar wind, is required for generation of Alfvén wings at Mercury. Assuming crustal conductances above this value it is demonstrated that currents in the Alfvén wings and closing across the planetary surface will produce significant perturbations (≥10 nT) of the magnetospheric magnetic field.