Magnetic reconnection as a mechanism to produce multiple protonpopulations and beams locally in the solar wind

Abstract

Context. Spacecraft observations early revealed frequent multiple proton populations in the solar wind. Decades of research on their origin have focused on processes such as magnetic reconnection in the low corona and wave-particle interactions in the corona and locally in the solar wind.Aims.This study aims to highlight that multiple proton populations and beams are also produced by magnetic reconnection occurring locally in the solar wind. Methods. We use high resolution Solar Orbiter proton velocity distribution function measurements, complemented by electron and magnetic field data, to analyze the association of multiple proton populations and beams with magnetic reconnection during a period of slow Alfvénic solar wind on 16 July 2020. Results. At least 6 reconnecting current sheets with associated multiple proton populations and beams, including a case of magnetic reconnection at a switchback boundary, are found during this day. This represents 2% of the measured distribution functions. We discuss how this proportion may be underestimated, and how it may depend on solar wind type and distance from the Sun. Conclusions. Although suggesting a likely small contribution, but which remains to be quantitatively assessed, Solar Orbiter observations show that magnetic reconnection must be considered as one of the mechanisms that produce multiple proton populations and beams locally in the solar wind.

References in corpus (7)

• Parker Solar Probe observations of proton beams simultaneous with ion-scale waves
• Parker Solar Probe In-Situ Observations of Magnetic Reconnection Exhausts During Encounter 1
• Ion kinetic energy conservation and magnetic field strength constancy in multi-fluid solar wind Alfvénic turbulence
• Inferred Linear Stability of Parker Solar Probe Observations using One- and Two-Component Proton Distributions
• In situ measurements of the variable slow solar wind near sector boundaries
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• Electromagnetic Ion-Ion Instabilities in Space Plasmas: Effects of Suprathermal Populations

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• Evidence of oblique electron acoustic solitary waves triggered by magnetic reconnection in Earth's magnetosphere
• Effect of the electronic pressure on the energy and magnetic moment of charged test particles in turbulent electromagnetic fields
• Anisotropic Heating and Parallel Heat Flux in Electron-only Magnetic Reconnection with Intense Guide Fields
• Hybrid simulations of the proton beam instabilities in the young solar wind. The formation of hammerhead-like distributions