Using a newly constructed map of the entire Sun, the possible sites of origin of the Sun’s slow solar wind are identified in research published in Nature Communications this week. The map was constructed from specially designed, full-disk observations from the Hinode satellite, together with a magnetic field model.
Fast (greater than 700km per second) and slow (approximately 400km per second) winds stream from the Sun, permeate the heliosphere, and influence the near-Earth environment. While the fast wind is known to emanate primarily from holes near the Sun’s poles, the source of the slow wind remains unknown. Understanding the flow of energy and matter throughout the solar system is a fundamental goal of heliophysics, and identifying the solar sources of this flow would be a major step forward in achieving that objective.
David Brooks and colleagues derived pure temperature images of the full Sun at the highest spatial resolution yet achieved, along with Doppler velocity maps of the corona extending to higher temperatures than previously possible. They also computed the first plasma composition map of the entire Sun. By combining these observations with a magnetic field extrapolation model, they constructed a unique slow wind sources map. Their results support the view that the slow wind flows from several contributing sources, such as active region outflows and an unknown source possibly located in the higher corona.