An Extended and Fragmented Alfvén Zone in the Young Solar Wind

Abstract

Motivated by theoretical, numerical, and observational evidence, we explore the possibility that the critical transition between sub-Alfvénic flow and super-Alfvénic flow in the solar atmosphere takes place in fragmented and disconnected subvolumes within a general Alfvén critical zone. The initial observations of sub-Alfvénic periods by Parker Solar Probe near \(16~R_\odot\) do not yet provide sufficient evidence to distinguish this possibility from that of a folded surface that separates simply-connected regions. Subsequent orbits may well enable such a distinction, but here we use a global magnetohydrodynamic model of the solar wind, coupled to a turbulence transport model, to generate possible realizations of such an Alfvén critical zone. Understanding this transition will inform theories of coronal heating, solar wind origin, solar angular momentum loss, and related physical processes in stellar winds beyond the Sun.

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Cited by in corpus (10)

• Defining the Middle Corona
• Prediction and Verification of Parker Solar Probe Solar Wind Sources at 13.3 R${}_{\odot }$
• Magnetic field intermittency in the solar wind: PSP and SolO observations ranging from the Alfven region out to 1 AU
• On the Generation and Evolution of Switchbacks and the Morphology of Alfvénic Transition: Low Mach-number Boundary Layers
• Anisotropic Magnetic Turbulence in the Inner Heliosphere -- Radial Evolution of Distributions observed by Parker Solar Probe
• Polarimeter to Unify the Corona and Heliosphere (PUNCH)
• Observed Fluctuation Enhancement and Departure from WKB Theory in Sub-Alfvénic Solar Wind
• The effect of turbulence on the angular momentum of the solar wind
• Reconstructing the Sun's Alfvén surface and wind braking torque with Parker Solar Probe
• Isotropization and Evolution of Energy-Containing Eddies in Solar Wind Turbulence: Parker Solar Probe, Helios 1, ACE, WIND, and Voyager 1