On the origin of switchbacks observed in the solar wind

Abstract

The origin of switchbacks in the solar wind is discussed in two classes of theory that differ in the location of the source being either in the transition region near the Sun or in the solar wind, itself. The two classes of theory differ in their predictions of the switchback rate as a function of distance from the Sun. To test these theories, one-hour averages of Parker Solar Probe data were summed over orbits three through seven. It is found that: 1. The average switchback rate was independent of distance from the Sun. 2. The average switchback rate increased with solar wind speed. 3. The switchback size perpendicular to the flow increased as R, the distance from the Sun, while the radial size increased as R2, resulting in a large and increasing switchback aspect ratio with distance from the Sun. 4. The switchback rotation angle did not depend on either the solar wind speed or the distance from the Sun. These results are consistent with switchback formation in the transition region because their increase of tangential size with radius compensates for the radial falloff of their equatorial density to produce switchback rates that are independent of distance from the Sun. This constant observed switchback rate is inconsistent with an in situ source. Once formed, the switchback size and aspect ratio, but not the rotation angle, increased with radial distance to at least 100 solar radii. In addition, quiet intervals between switchback patches occurred at the lowest solar wind speeds.

arXiv comment10 figures and an appendix with four more figures

References in corpus (12)

• Observing the Roots of Solar Coronal Heating - in the Chromosphere
• Switchbacks in the near-Sun magnetic field: long memory and impact on the turbulence cascade
• Generation of Solar Spicules and Subsequent Atmospheric Heating
• In-situ switchback formation in the expanding solar wind
• Switchbacks as signatures of magnetic flux ropes generated by interchange reconnection in the corona
• Shear-Driven Transition to Isotropically Turbulent Solar Wind Outside the Alfven Critical Zone
• Magnetic field kinks and folds in the solar wind
• Fading Coronal Structure and the Onset of Turbulence in the Young Solar Wind
• Cross Helicity Reversals In Magnetic Switchbacks
• Localized magnetic field structures and their boundaries in the near-Sun solar wind from Parker Solar Probe measurements
• Statistical analysis of orientation, shape, and size of solar wind switchbacks
• Could switchbacks originate in the lower solar atmosphere? I. Formation mechanisms of switchbacks

Cited by in corpus (5)

• Parker Solar Probe: Four Years of Discoveries at Solar Cycle Minimum
• Observation of Magnetic Switchback in the Solar Corona
• Patches of magnetic switchbacks and their origins
• Flux rope merging and the structure of switchbacks in the solar wind
• On the formation of solar wind & switchbacks, and quiet Sun heating