Identifying the Coronal Source Regions of Solar Wind Streams from Total Solar Eclipse Observations and in situ Measurements Extending over a Solar Cycle

journal article in Web of Science

en

This letter capitalizes on a unique set of total solar eclipse observations acquired between 2006 and 2020 in white light, Fe xi 789.2 nm (T-fexi = 1.2 0.1 MK), and Fe xiv 530.3 nm (T-fexiv = 1.8 0.1 MK) emission complemented by in situ Fe charge state and proton speed measurements from Advanced Composition Explorer/SWEPAM-SWICS to identify the source regions of different solar wind streams. The eclipse observations reveal the ubiquity of open structures invariably associated with Fe xi emission from Fe10+ and hence a constant electron temperature, T-c = T-fexi, in the expanding corona. The in situ Fe charge states are found to cluster around Fe10+, independently of the 300-700 km s(-1) stream speeds, referred to as the continual solar wind. Thus, Fe10+ yields the fiducial link between the continual solar wind and its T-fexi sources at the Sun. While the spatial distribution of Fe xiv emission from Fe13+ associated with streamers changes throughout the solar cycle, the sporadic appearance of charge states >Fe11+ in situ exhibits no cycle dependence regardless of speed. These latter streams are conjectured to be released from hot coronal plasmas at temperatures >= T-fexiv within the bulge of streamers and from active regions, driven by the dynamic behavior of prominences magnetically linked to them. The discovery of continual streams of slow, intermediate, and fast solar wind characterized by the same T-fexi in the expanding corona places new constraints on the physical processes shaping the solar wind.

This letter capitalizes on a unique set of total solar eclipse observations acquired between 2006 and 2020 in white light, Fe xi 789.2 nm (T-fexi = 1.2 0.1 MK), and Fe xiv 530.3 nm (T-fexiv = 1.8 0.1 MK) emission complemented by in situ Fe charge state and proton speed measurements from Advanced Composition Explorer/SWEPAM-SWICS to identify the source regions of different solar wind streams. The eclipse observations reveal the ubiquity of open structures invariably associated with Fe xi emission from Fe10+ and hence a constant electron temperature, T-c = T-fexi, in the expanding corona. The in situ Fe charge states are found to cluster around Fe10+, independently of the 300-700 km s(-1) stream speeds, referred to as the continual solar wind. Thus, Fe10+ yields the fiducial link between the continual solar wind and its T-fexi sources at the Sun. While the spatial distribution of Fe xiv emission from Fe13+ associated with streamers changes throughout the solar cycle, the sporadic appearance of charge states >Fe11+ in situ exhibits no cycle dependence regardless of speed. These latter streams are conjectured to be released from hot coronal plasmas at temperatures >= T-fexiv within the bulge of streamers and from active regions, driven by the dynamic behavior of prominences magnetically linked to them. The discovery of continual streams of slow, intermediate, and fast solar wind characterized by the same T-fexi in the expanding corona places new constraints on the physical processes shaping the solar wind.

Solar prominences; Solar cycle; Solar wind; Total eclipses; Solar coronal streamers; Solar magnetic fields; Solar coronal heating; Solar coronal mass ejections; Solar corona

12.04.2021

IOP PUBLISHING LTD

BRISTOL

2041-8205

911

1

1–14

14