Numerical MHD Simulation on 3D Morphology and Kinematics of the 2017 September 10 CME-driven Shock from Sun to Earth

A global, three-dimensional (3D) numerical simulation model has been employed to study the 3D morphology and kinematics of the large shock driven by the 2017 September 10 coronal mass ejection (CME). Based on actual solar observations, which include the photospheric magnetic field and the CME’s speed and source location, the simulation result is delicately tuned by matching coronal polarized brightness observations and in situ solar wind measurements at 1 AU. The simulation reproduces well the shock’s shape and position in coronagraph images. The shock’s physical parameters at 1 AU approach to realistic observations, with the transit time being nearly the same as the observed one. The simulation reveals that the shock around the backward direction keeps propagating away from the Sun, and despite large extent, the shock can not be seen as a spherical structure with 360◦ envelope around the Sun. Identified as a fast forward shock, the shock with the sharp velocity jump and the large density compression has its Mach number larger than 1 from the nose toward the lateral parts, consistentwith a driven shock all across the front. Compared to the nose, the right flank of the shock has the weak compression ratio, but probably yields the enhanced energetic particles for observers aligned with it. It follows that large CME-driven shocks have the potential to accelerate energetic particles over the wide longitudinal separation and are likely responsible for the production of these particles in the inner heliosphere.