Solar Physics

, Volume 256, Issue 1, pp 327–344

Small Solar Wind Transients and Their Connection to the Large-Scale Coronal Structure

  • E. K. J. Kilpua
  • J. G. Luhmann
  • J. Gosling
  • Y. Li
  • H. Elliott
  • C. T. Russell
  • L. Jian
  • A. B. Galvin
  • D. Larson
  • P. Schroeder
  • K. Simunac
  • G. Petrie
Open Access
STEREO SCIENCE RESULTS AT SOLAR MINIMUM

DOI: 10.1007/s11207-009-9366-1

Cite this article as:
Kilpua, E.K.J., Luhmann, J.G., Gosling, J. et al. Sol Phys (2009) 256: 327. doi:10.1007/s11207-009-9366-1

Abstract

It has been realized for some time that the slow solar wind with its embedded heliospheric current sheet often exhibits complex features suggesting at least partially transient origin. In this paper we investigate the structure of the slow solar wind using the observations by the Wind and STEREO spacecraft during two Carrington rotations (2054 and 2055). These occur at the time of minimum solar activity when the interplanetary medium is dominated by recurrent high-speed streams and large-scale interplanetary coronal mass ejections (ICMEs) are rare. However, the signatures of transients with small scale-sizes and/or low magnetic field strength (comparable with the typical solar wind value, ∼ 5 nT) are frequently found in the slow solar wind at these times. These events do not exhibit significant speed gradients across the structure, but instead appear to move with the surrounding flow. Source mapping using models based on GONG magnetograms suggests that these transients come from the vicinity of coronal source surface sector boundaries. In situ they are correspondingly observed in the vicinity of high density structures where the dominant electron heat flux reverses its flow polarity. These weak transients might be indications of dynamical changes at the coronal hole boundaries or at the edges of the helmet streamer belt previously reported in coronagraph observations. Our analysis supports the idea that even at solar minimum, a considerable fraction of the slow solar wind is transient in nature.

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Copyright information

© The Author(s) 2009

Authors and Affiliations

  • E. K. J. Kilpua
    • 1
    • 2
  • J. G. Luhmann
    • 2
  • J. Gosling
    • 3
  • Y. Li
    • 2
  • H. Elliott
    • 4
  • C. T. Russell
    • 5
  • L. Jian
    • 5
  • A. B. Galvin
    • 6
  • D. Larson
    • 2
  • P. Schroeder
    • 2
  • K. Simunac
    • 6
  • G. Petrie
    • 7
  1. 1.Department of Physical Sciences, Theoretical Physics DivisionUniversity of HelsinkiHelsinkiFinland
  2. 2.Space Sciences LaboratoryUniversity of CaliforniaBerkeleyUSA
  3. 3.Laboratory for Atmospheric and Space PhysicsUniversity of ColoradoBoulderUSA
  4. 4.Southwest Research InstituteSan AntonioUSA
  5. 5.Institute of Geophysics and Planetary PhysicsUCLALos AngelesUSA
  6. 6.Institute for the Study of Earth, Oceans, and SpaceUniversity of New HampshireDurhamUSA
  7. 7.National Solar ObservatoryTucsonUSA

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