Heliospheric Current Sheet Distortions from Adjacent Outflowing Transients: Multi-spacecraft Observations

Abstract

The heliospheric current sheet (HCS) is a permanent solar wind feature, with well predicted Earth passages, but it can be structured and its main orientation can be highly distorted. We report new observations from 2 spacecraft in the solar wind (supported by observations from 3 spacecraft in the nightside magnetosheath), showing an evolution across the Sun-Earth line of large field reversals adjacent to the HCS. Contrary to a previously reported multi-spacecraft event, this case shows that the field inversion structure cannot be assumed to be well preserved and close to planar on the scale of the magnetospheric cross-section. However, both cases indicate the presence of field reversals in an away sector that is connected to the southern solar magnetic hemisphere but lies unexpectedly above a toward sector. Following the interpretation of the reversals as transient outflowing loops, associated initial flow deviations can be envisaged to account for the HCS deformations.