Joint observations of magnetic switchbacks from BepiColombo and Solar Orbiter in the inner heliosphere

Since Parker, the existence of the solar wind has been ascribed to the fact that the solar corona is not in hydrostatic equilibrium and thus is constantly expanding. However, the mechanism responsible for accelerating/heating the solar wind is widely debated, even though there is evidence that it is magnetic in nature. New space missions like Parker Solar Probe (PSP), Solar Orbiter (SolO) and BepiColombo (BC), being much closer to the Sun, allow observations of less evolved and less mixed solar wind. Thus, for example, the observed streams can be easily back-propagated to their source on the Sun, allowing generally more accurate characterizations. These new observations revealed that the measured magnetic field is highly structured close to the Sun, exhibiting patches of large and intermittent reversals associated with jets of plasma. Jetting activity reveals that the solar wind emission is discrete in nature rather than homogeneous, leading to intermittent/impulsive outflow from the corona driven by small-scale magnetic reconnection. In a recent work, it has been shown that super granulation structure at the coronal base remains imprinted in the near-Sun solar wind, resulting in the magnetic polarity inversions known as switchback. Farther from the Sun, however, switchbacks are less frequent, probably due to mixing and turbulent decay.

According to the Potential Field Source Surface extrapolation between 6th and 7th October 2021, BC and SolO were connected to the same region on the Sun. BC and SolO were located at 0.36 AU and 0.67 AU, respectively. Both spacecraft detected a patch of switchbacks, offering the opportunity to investigate their evolution with solar wind propagation. Our findings highlight the potential of BC for synergistic studies with PSP and SolO, despite its primary focus on Mercury’s environment.