Three-dimensional lunar wake reconstructed from ARTEMIS data
【摘要】：Data from the two-spacecraft Acceleration,Reconnection,Turbulence and Electrodynamics of the Moon's Interaction with the Sun mission to the IVloon have been exploited to characterize the lunar wake with unprecedented fidelity.The differences between measurements made by a spacecraft in the solar wind very near the IVloon and concurrent measurements made by a second spacecraft in the near lunar wake are small but systematic.They enabled us to establish the perturbations of plasma density,temperature,thermal,magnetic and total pressure,field,and flow downstream of the IVloon to distances of 12 lunar radii(R_M).The wake disturbances are initiated immediately behind the IVloon by the diamagnetic currents at the lunar terminator.Rarefaction waves propagate outward at fast MHD wave velocities.Beyond ~6.5 R_M',all plasma and field parameters are poorly structured which suggests the presence of instabilities excited by counter-streaming particles.Inward flowing plasma accelerated through pressure gradient force and ambipolar electric field compresses the magnetic field and leads to continuous increase in magnitude of magnetic perturbations.Besides the downstream distance,the field perturbation magnitude is also a function of the solar wind ion beta and the angle between the solar wind and the interplanetary magnetic field(IMF).Both ion and electron temperatures increase as a consequence of an energy dispersion effect,whose explanation requires fully kinetic models.Downstream of the Moon,the IMF field lines are observed to bulge toward the Moon,which is unexpected and may be caused by a plasma pressure gradient force or/and the pickup of heavy charged dust grains behind the Moon.
【作者单位】：Key Laboratory of Earth and Planetary Physics,Institute of Geology and Geophysics,Chinese Academy of Sciences Beijing National Observatory of Space Environment,Institute of Geology and Geophysics,Chinese Academy of Sciences State Key Laboratory of Space Weather,Chinese Academy of Sciences Department of Earth and Space Sciences,University of California Atmospheric,Oceanic and Space Sciences Department,University of Michigan School of Earth and Space Sciences,Peking University School of Space Science and Physics,Shangdong University at Weihai School of Astronautics,Beihang University 【基金】：supported by the National Science Foundation of China (41274171)
the specialized research fund for Chinese State Key Laboratories under project Y22612A33S
the Chinese Academy of Sciences project(KZZD-EW01-3)
the Scientific and Technological Innovation and Cooperation Group of Chinese Academy of Sciences
the Hundred Talent Program of Chinese Academy of Sciences
supported by NASA through THEMIS 443869-TM-22620 and THEMIS/ ARTEMIS project NAS5-02099 【分类号】：