Fast prograde coronal flows in solar active regions
Chamberlin, Phillip C.; Fletcher, Lyndsay; Mulay, Sargam M.; Woods, Thomas N.; Hudson, Hugh S.; Docherty, Jennifer; Fitzpatrick, Jimmy; Pike, Eleanor; Strong, Morven
United Kingdom, United States, Norway
Abstract
We report the discovery and characterization of high-speed (>100 km s-1) horizontal flows in solar active regions, making use of the Sun-as-a-star spectroscopy in the range 5-105 nm provided by the EVE (Extreme Ultraviolet Variability Experiment) spectrometers on the Solar Dynamics Observatory. These apparent flows are persistent on time-scales of days, and are well observed in lines of Mg X, Si XII, and Fe XVI for example. They are prograde, as evidenced directly by blueshifts/redshifts peaking at the east/west limb passages of isolated active regions. The high-speed flow behaviour does not depend upon active-region latitude or solar cycle, with similar behaviour in Cycles 24 and 25.