Magnetic Field Reconnection as the Source of the Solar wind

Solar and stellar winds are ubiquitous flows of charged particles (i.e., electrons, protons, and heavier ions) permeating the stellar spheres (Neugebauer & Snyder 1962). Through these winds, stars lose angular momentum, slow down their rotation as they mature, shape planetary systems, and affect the composition and the physical and chemical evolution of planetary atmospheres and, consequently, the habitability of these planets (Lüftinger et al. 2015; Gallet et al. 2017). How the solar wind is generated at the source, heated, and accelerated, and what is its nature (i.e., continuous vs. intermittent flow) are long-standing fundamental questions. Here we show that the physical mechanism that drives the solar wind at its source regions is ubiquitous magnetic field reconnection in the form of small-scale jetting activity (i.e., jetlets; Raouafi & Stenborg 2014). We find that jetlets, like the solar wind, are universal regardless of the solar cycle phase. Each event is the product of reconnection of opposite polarity magnetic fields producing a short-lived jet of hot plasma and Alfvén waves into the corona. The sheer number of these discrete jetlet events leads to an intermittent flow in the corona, which homogenizes as it propagates away from the Sun. This flow forms the solar wind. This discovery hones in on the importance of small-scale magnetic field reconnection in the solar and stellar atmospheres to historical phenomena such as the coronal heating problem and solar wind acceleration.

References

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