A Study of an Equatorial Coronal Hole Observed at the First Parker Solar Probe Perihelion

Abstract

Abstract In this study, we present an observational analysis of a coronal hole (CH) observed on 2018 November 1 and solar wind (SW) that originated from it, using the Solar Dynamics Observatory, the Parker Solar Probe (PSP) observations at 68 solar radii, ACE and WIND data at 1 au, and interplanetary scintillation (IPS) observations from 0.2 to 1 au. The CH-originated SW stream was observed by L1 on 2018 November 4 and by PSP on 2018 November 15. We examined the CH for nine Carrington Rotations (CR) and find that the SW stream to reach L1 varied from one CR to other. We find that the pressure, temperature, and magnetic fields increase as the speed of the SW increases and the density decreases with distance. We noticed suprathermal particle enhancement at and after the stream interaction region in both PSP and L1 observations, but the enhancement lasted longer in PSP compared to measurements made at L1. The multiple-rotation observations of the CH imply that any differences in observations between PSP and spacecraft at L1 are due to the radial evolution of the solar wind stream rather than of the CH or the source plasma itself. In addition, IPS measured the radio signal irregularities driven by the SW. Furthermore, we employed a standard analytical model to extrapolate the magnetic field at larger heights. We find that the extrapolated magnetic field at 68 R ⊙ and 1 au matches well with the magnetic field measured by PSP and OMNI.