Abstract
This study analyzes the flux transfer event (FTE)-type flux ropes and magnetic reconnection around the dayside magnetopause during BepiColombo’s Earth flyby. The magnetosheath corresponds to a high plasma β (~ 8) and the IMF has a significant radial component. Six flux ropes are identified. The motion of flux rope together with the maximum magnetic shear model suggests that the reconnection X-line swipes BepiColombo near the magnetic equator due to an increase of the radial IMF. The flux rope with the highest flux content contains a clear coalescence signature, i.e., two smaller flux ropes merging, supporting theoretical predictions the flux content of flux ropes can grow through coalescence. The secondary reconnection associated with coalescence exhibits a large normalized guide field and a reconnection rate comparable to the reconnection rate measured at the magnetopause (~ 0.1).
Highlights
25 Flux transfer events (FTEs) are frequently observed near the outer boundaries of planetary magnetospheres, including at the Earth (e.g., Russell and Elphic, 1978; Saunders et al, 1984; Wang et al, 2005), Mercury (Russell and Walker, 1985; Slavin et al, 2009; 2010; 2012; Imber et al, 2014; Sun et al, 2020), Saturn (Jasinski et al, 2016; 2021) and Jupiter (Walker and Russell, 1985; Lai et al, 2012)
The traveling of the FTE-type flux rope suggests that the X-line crosses the location of BepiColombo, which is verified by the motion of the X-lines obtained from the maximum magnetic shear model
The FTE-type flux ropes have scales ranging from several di to around 20 di, and the FTE-type flux rope with a large scale and the highest magnetic flux content corresponds to a clear coalescence signature
Summary
25 Flux transfer events (FTEs) are frequently observed near the outer boundaries of planetary magnetospheres, including at the Earth (e.g., Russell and Elphic, 1978; Saunders et al, 1984; Wang et al, 2005), Mercury (Russell and Walker, 1985; Slavin et al, 2009; 2010; 2012; Imber et al, 2014; Sun et al, 2020), Saturn (Jasinski et al, 2016; 2021) and Jupiter (Walker and Russell, 1985; Lai et al, 2012). Some of the FTEs have magnetic flux ropes at their cores, which consist of helical magnetic field lines surrounding stronger magnetic fields paralleling their central 30 axes (Paschmann et al, 1982; Lee et al, 1993) These FTE-type flux ropes are created by multiple X-line reconnections in the magnetopause during intervals of significant magnetic shear across this current sheet (Lee and Fu, 1985; Raeder, 2006).
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call