Flying through an Eruption-associated Magnetic Reconnection Current Sheet in the Solar Corona

Abstract Magnetic reconnection is a universal and fundamental process occurring in highly conductive magnetized plasma where field lines of opposite polarity reconfigure to a lower energy state across different scales. It plays a vital role in shaping the dynamics of the solar corona and heliosphere. It is also known to be responsible for energy exchange processes in Earth's magnetosphere, magnetic systems of our solar system planets and other astrophysical systems including black holes, blazars, and quasars. Theoretical models and laboratory experiments have predicted various properties of magnetic reconnection and associated flares, eruptions and current sheets at different spatio-temporal scales, which are complemented by remote sensing imaging observations. However, in situ sampling of plasma properties of reconnection regions after an eruption in the solar corona was impossible prior to the launch of Parker Solar Probe, with its close-in perihelion. Here we report on in situ observations of an ongoing reconnection event in the solar corona from PSP at a distance of 14 R⊙, supported by complementary remote sensing observations from Solar Orbiter. We find that even after more than 24 hours of the flare peak emission, PSP detected reconnection exhaust, suggesting ongoing fast reconnection. The observed plasma parameters in this region match well with predictions based on computer simulations. Solar Orbiter's observations of the low corona, and PSP's measurements in the outer corona, suggest that some magnetic environments support reconnection that lasts longer than the typical time-scales of a few minutes to a few hours generally inferred from remote sensing observations of the solar corona at various scales. These observations provide a key bridge to understand the relationship between observational and theoretical aspects of laboratory-based plasma experiments and plasmas in the solar atmosphere and astrophysical systems.