Searching for a Solar Source of Magnetic-Field Switchbacks in Parker Solar Probe's First Encounter

Parker Solar Probe observations show ubiquitous magnetic-field reversals closer to the Sun, often referred to as switchbacks. The switchbacks have been observed before in the solar wind near 1 AU and beyond, but their occurrence was historically rare. PSP measurements below similar to 0.2 AU show that switchbacks are, however, the most prominent structures in the young solar wind. In this work, we analyze remote-sensing observations of a small equatorial coronal hole to which PSP was connected during the perihelion of Encounter 1. We investigate whether some of the switchbacks captured during the encounter were of coronal origin by correlating common switchback in situ signatures with remote observations of their expected coronal footpoint. We find strong evidence that timescales present in the corona are relevant to the outflowing, switchback-filled solar wind, as illustrated by strong linear correlation. We also determine that spatial analysis of the observed region is optimal, as the implied average solar-wind speed more closely matches that observed by PSP at the time. We observe that hemispherical structures are strongly correlated with the radial proton velocity and the mass flux in the solar wind. The above findings suggest that a subpopulation of the switchbacks are seeded at the corona and travel into interplanetary space.

Automated summary

Observations from Parker Solar Probe show the presence of magnetic-field reversals, known as switchbacks, closer to the Sun. These switchbacks were historically rare in the solar wind beyond 1 AU, but are the most prominent structures in the young solar wind below 0.2 AU. By analyzing remote-sensing observations of a small coronal hole connected to PSP, researchers found strong evidence that some of the switchbacks captured during the encounter originated from the corona and traveled into interplanetary space.