Coronal Holes, Magnetic Network, and the High-Speed Solar Wind

Coronal Holes, Magnetic Network, and the High-Speed Solar Wind

. Dark coronal holes at the Sun’s polar regions (top and bottom) are the source of much of the high-speed solar wind. The inset provides a close-up, Doppler velocity map of the million-degree gas at the base of the corona where the fast solar wind originates, taken in the extreme ultraviolet light of ionized neon (the Ne VIII line at 77.0 nanometers). Dark blue represents an outflow, or blueshift, at a velocity of 10,000 meters per second; it marks the beginning of the high-speed solar wind. Dark red indicates a downflow at the same speed. Superposed are the edges of the “honey-comb” shaped pattern of the magnetic network, where the strongest outward flows (dark blue) are found. The relationship between the outflow velocities and the network suggests that the high-speed wind emanates from the boundaries and boundary intersections of the magnetic network. These observations were taken on 22 September 1996. [Courtesy of the SOHO EIT consortium (full disk) and the SOHO SUMER consortium (velocity inset). SOHO is a project of international collaboration between ESA and NASA.]

Copyright 2010, Professor Kenneth R. Lang, Tufts University