Space Science Reviews

, Volume 101, Issue 3, pp 229–294

Coronal Holes and the High-Speed Solar Wind

  • Steven R. Cranmer

DOI: 10.1023/A:1020840004535

Cite this article as:
Cranmer, S.R. Space Science Reviews (2002) 101: 229. doi:10.1023/A:1020840004535


Coronal holes are the lowest density plasma components of the Sun's outer atmosphere, and are associated with rapidly expanding magnetic fields and the acceleration of the high-speed solar wind. Spectroscopic and polarimetric observations of the extended corona, coupled with interplanetary particle and radio sounding measurements going back several decades, have put strong constraints on possible explanations for how the plasma in coronal holes receives its extreme kinetic properties. The Ultraviolet Coronagraph Spectrometer (UVCS) aboard the Solar and Heliospheric Observatory (SOHO) spacecraft has revealed surprisingly large temperatures, outflow speeds, and velocity distribution anisotropies for positive ions in coronal holes. We review recent observations, modeling techniques, and proposed heating and acceleration processes for protons, electrons, and heavy ions. We emphasize that an understanding of the acceleration region of the wind (in the nearly collisionless extended corona) is indispensable for building a complete picture of the physics of coronal holes.

Copyright information

© Kluwer Academic Publishers 2002

Authors and Affiliations

  • Steven R. Cranmer
    • 1
  1. 1.Harvard-Smithsonian Center for AstrophysicsCambridgeUSA