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

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Crooker, N. U. ; Appleton, E. M. ; Schwadron, N. A. ; Owens, M.J. (2010)
  • Publisher: American Geophysical Union
  • Related identifiers: doi: 10.1029/2010JA015496
  • Subject:
    arxiv: Physics::Space Physics | Astrophysics::Solar and Stellar Astrophysics

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