Fig. 1: Projections of BepiColombo’s third Mercury flyby trajectory in the aberrated Mercury–Sun magnetospheric (aMSM) coordinate system.
From: Mercury’s plasma environment after BepiColombo’s third flyby
a X'–Z' and (b) X'–Y' planes, all expressed in Mercury radii (RM ≈ 2440 km). Note the displacement in (a) of the magnetopause relative to the planetary center because of the northward offset of the magnetic dipole by ~0.2 RM. In traditional MSM coordinates, the X-axis and Z-axis point to the sun and north pole, respectively, and the Y-axis completes a right-hand system. In the aberrated coordinates, Mercury’s orbital velocity is considered. The X-axis is anti-parallel to the solar wind direction in the rest of the reference frame of Mercury. The aberration angle varies between −5.5° and −8.4° assuming a solar wind speed of 400 km/s. The black arrows indicate the viewing direction of MSA during this flyby. The magenta and cyan crosses represent the observed inbound (and outbound) bow shock and magnetopause crossings, respectively (see Fig. 2). The red dot highlights the closest approach of BepiColombo to Mercury. The black solid and dashed lines represent the modeled dayside bow shock and magnetopause that are obtained from the statistical distribution of observed crossing points40, respectively.
