The Magnetic Structure of the Subsolar MPB Current Layer From MAVEN Observations: Implications for the Hall Electric Force

Abstract : We report on the local structure of the Martian subsolar magnetic pileup boundary (MPB) from minimum variance analysis of the magnetic field measured by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft for six orbits. In particular, we detect a well-defined current layer within the MPB and provide a local estimate of its current density which results in a sunward Hall electric force. This force accounts for the deflection of the solar wind ions and the acceleration of electrons which carry the interplanetary magnetic field through the MPB into the magnetic pileup region. We find that the thickness of the MPB current layer is of the order of both the upstream (magnetosheath) solar wind proton inertial length and convective gyroradius. This study provides a high-resolution view of one of the components of the current system around Mars reported in recent works.