Predictions for the First Parker Solar Probe Encounter

Abstract

We examine Alfvén Wave Solar atmosphere Model (AWSoM) predictions of the first Parker Solar Probe (PSP) encounter. We focus on the 12 day closest approach centered on the first perihelion. AWSoM allows us to interpret the PSP data in the context of coronal heating via Alfvén wave turbulence. The coronal heating and acceleration is addressed via outward-propagating low-frequency Alfvén waves that are partially reflected by Alfvén speed gradients. The nonlinear interaction of these counter-propagating waves results in a turbulent energy cascade. To apportion the wave dissipation to the electron and anisotropic proton temperatures, we employ the results of the theories of linear wave damping and nonlinear stochastic heating as described by Chandran et al. We find that during the first encounter, PSP was in close proximity to the heliospheric current sheet (HCS) and in the slow wind. PSP crossed the HCS two times, at 2018 November 3 UT 01:02 and 2018 November 8 UT 19:09, with perihelion occurring on the south of side of the HCS. We predict the plasma state along the PSP trajectory, which shows a dominant proton parallel temperature causing the plasma to be firehose unstable.