Interchange reconnection as the source of the fast solar wind within coronal holes

Abstract

The fast solar wind that fills the heliosphere originates from deep within regions of open magnetic field on the Sun called coronal holes. The energy source responsible for accelerating the plasma to high speeds is widely debated, however there is evidence that it is ultimately magnetic in nature with candidate mechanisms including wave heating^(1,2) and interchange reconnection^(3,4,5). The coronal magnetic field near the solar surface is structured on scales associated with supergranulation convection cells, where descending flows create intense fields. The energy density in these network magnetic field bundles is a likely candidate as an energy source of the wind. Here we report measurements of fast solar wind streams from the Parker Solar Probe (PSP) spacecraft^6 which provides strong evidence for the interchange reconnection mechanism. We show that supergranulation structure at the coronal hole base remains imprinted in the near-Sun solar wind resulting in asymmetric patches of magnetic 'switchbacks'^(7,8) and bursty wind streams with power law-like energetic ion spectra to beyond 100 keV. Computer simulations of interchange reconnection support key features of the observations, including the ion spectra. Important characteristics of interchange reconnection in the low corona are inferred from the data including that the reconnection is collisionless and that the energy release rate is sufficient to power the fast wind. In this scenario, open magnetic flux undergoes continuous reconnection and the wind is driven both by the resulting plasma pressure and the radial Alfvenic flow bursts.

15 pages, 4 figures. Nature, 2023

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Cited by in corpus (27)

• In situ observations of large amplitude Alfvén waves heating and accelerating the solar wind
• Picoflare jets power the solar wind emerging from a coronal hole on the Sun
• Quantifying the Energy Budget in the Solar Wind from 13.3-100 Solar Radii
• New Evidence on the Origin of Solar Wind Microstreams/Switchbacks
• Coronal hole picoflare jets are progenitors of both fast and Alfvénic slow solar wind
• Coronal Heating and Solar Wind Generation by Flux Cancellation Reconnection
• Solar Spicules, Filigrees and Solar Wind Switchbacks
• Cross Helicity and the Helium Abundance as an in situ Metric of Solar Wind Acceleration
• Propagation of untwisting solar jets from the low-beta corona into the super-Alfvénic wind: Testing a solar origin scenario for switchbacks
• The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations
• Magnetic reconnection-driven energization of protons up to 400 keV at the near-Sun heliospheric current sheet
• Thin coronal jets and plasmoid-mediated reconnection: Insights from Solar Orbiter observations and Bifrost simulations
• Tracing magnetic switchbacks to their source: An assessment of solar coronal jets as switchback precursors
• On the transition from Slow to Fast Wind as Observed in Composition Observations
• Dominance of 2-Minute Oscillations near the Alfvén Surface
• Testing the flux tube expansion factor -- solar wind speed relation with Solar Orbiter data
• On the short term stability and tilting motion of a well-observed low-latitude solar coronal hole
• Switchbacks near Boundaries of Small-scale Magnetic Flux Ropes in the Young Solar Wind from Parker Solar Probe Observations
• Formation of Magnetic Switchbacks via expanding Alfvén Waves
• Solar Wind Structures from the Gaussianity of Magnetic Magnitude
• Solar Alfvenic Pulses and Mesoscale Solar Wind
• Characterizing the Impact of Alfvén Wave Forcing in Interplanetary Space on the Distribution of near-Earth Solar Wind Speeds
• Asymmetry of the spectral lines of the coronal hole and quiet Sun in the transition region
• Two Types of $1/f$ Range in Solar Wind Turbulence
• Density fluctuation in the solar corona and solar wind: A comparative analysis of radio-occultation observations and magnetohydrodynamic simulation
• Proposal of a Novel Physical Parameter Characterizing Solar Wind Speed in a Wave-Driven Model
• What Determines the Brightness of the Magnetically Open Solar Corona?: Insights from Three-dimensional Radiative Magnetohydrodynamic Simulations and Observations