Suprathermal electron flux peaks at stream interfaces: Signature of solar wind dynamics or tracer for open magnetic flux transport on the Sun?

• Published in: Journal of Geophysical Research: Space Physics Vol. 115; no. A11
• Main Authors: Crooker, N. U., Appleton, E. M., Schwadron, N. A., Owens, M. J.
• Format: Journal Article
• Language: English
• Published: Washington, DC Blackwell Publishing Ltd 01.11.2010; American Geophysical Union
• Subjects: Astronomy; Astrophysics; coronal hole boundary; Earth sciences; Earth, ocean, space; Exact sciences and technology; Fluctuations; interchange reconnection; Magnetic fields; Planetology; Space; stream interaction region; Sun; Magnetic flux; Plasma; magnetic field; Pitch angle; variability; electrons; Superposed epoch analysis; dynamics; displacements; direction; Electron flux; interfaces; maps; tracers; streams; cartography; pressure; transport; Sun; solar wind; intensity; Solar rotation; Coronal hole; compression; Suprathermal particle
• ISSN: 0148-0227; 2169-9380; 2156-2202; 2169-9402
• DOI: 10.1029/2010JA015496

The high variability of the intensity of suprathermal electron flux in the solar wind is usually ascribed to the high variability of sources on the Sun. Here we demonstrate that a substantial amount of the variability arises from peaks in stream interaction regions, where fast wind runs into slow wind and creates a pressure ridge at the interface. Superposed epoch analysis centered on stream interfaces in 26 interaction regions previously identified in Wind data reveal a twofold increase in 250 eV flux (integrated over pitch angle). Whether the peaks result from the compression there or are solar signatures of the coronal hole boundary, to which interfaces may map, is an open question. Suggestive of the latter, some cases show a displacement between the electron and magnetic field peaks at the interface. Since solar information is transmitted to 1 AU much more quickly by suprathermal electrons compared to convected plasma signatures, the displacement may imply a shift in the coronal hole boundary through transport of open magnetic flux via interchange reconnection. If so, however, the fact that displacements occur in both directions and that the electron and field peaks in the superposed epoch analysis are nearly coincident indicate that any systematic transport expected from differential solar rotation is overwhelmed by a random pattern, possibly owing to transport across a ragged coronal hole boundary.