Possible Generation Mechanism for Compressional Alfvénic Spikes as Observed by Parker Solar Probe

Abstract

The solar wind is found by Parker Solar Probe (PSP) to be abundant with Alfvénic velocity spikes and magnetic field kinks. Temperature enhancement is another remarkable feature associated with the Alfvénic spikes. How the prototype of these coincident phenomena is generated intermittently in the source region becomes a hot topic of wide concerns. Here we propose a new model introducing guide-field discontinuity into the interchange magnetic reconnection between open funnels and closed loops with different magnetic helicities. The modified interchange reconnection model not only can accelerate jet flows from the newly opening closed loop but also excite and launch Alfvénic wave pulses along the newly-reconnected and post-reconnected open flux tubes. We find that the modeling results can reproduce the following observational features: (1) Alfvén disturbance is pulsive in time and asymmetric in space; (2) Alfvénic pulse is compressible with temperature enhancement and density variation inside the pulse. We point out that three physical processes co-happening with Alfvén wave propagation can be responsible for the temperature enhancement: (a) convection of heated jet flow plasmas (decrease in density), (b) propagation of compressed slow-mode waves (increase in density), and (c) conduction of heat flux (weak change in density). We also suggest that the radial nonlinear evolution of the Alfvénic pulses should be taken into account to explain the formation of magnetic switchback geometry.

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Cited by in corpus (12)

• Parker Solar Probe: Four Years of Discoveries at Solar Cycle Minimum
• Magnetic Reconnection as the Driver of the Solar Wind
• Oscillatory Reconnection of a 2D X-point in a hot coronal plasma
• The Structure and Origin of Switchbacks: Parker Solar Probe Observations
• On the properties of Alfvénic switchbacks in the expanding solar wind: the influence of the Parker spiral
• Oscillatory reconnection as a plasma diagnostic in the solar corona
• The Temperature, Electron, and Pressure Characteristics of Switchbacks: Parker Solar Probe Observations
• Analytic Model and Magnetohydrodynamic Simulations of Three-dimensional Magnetic Switchbacks
• Growth of Outward Propagating Fast-Magnetosonic/Whistler Waves in the Inner Heliosphere Observed by Parker Solar Probe
• Switchbacks near Boundaries of Small-scale Magnetic Flux Ropes in the Young Solar Wind from Parker Solar Probe Observations
• Detecting the oscillation and propagation of the nascent dynamic solar wind structure at 2.6 solar radii using VLBI radio telescopes
• The independence of oscillatory reconnection periodicity from the initial pulse