Transition-Region Blinkers - II. Active-Region Properties

Abstract

The distribution and general properties of events identified in an active region that have the same characteristics as quiet-Sun blinkers are discussed and named `active-region blinkers'. The events are identified using an automated scheme `BLinker Identification Program' (BLIP) which was designed for and tested on quiet-Sun blinkers. Like quiet-Sun blinkers, the active-region events are most easily identified in the 629 Å emission line from O v although evidence for them is also found in other extreme UV lines emitted from He i, O iii and O iv. Unlike quiet-Sun blinkers, however, they may also have coronal signatures in the lines Mg ix and Mg x. Their properties are very similar to those of quiet-Sun blinkers with mean lifetimes of 16-19 min, mean areas of 2.4-4.3×10⁷ km² and mean intensity enhancements factors of 1.8-3.3. Their global frequency of 7-28 s⁻¹ is about 42%-700% higher than that for quiet-Sun blinkers. The blinkers discussed here are found above both active-region (plage) magnetic fields, as well as above the umbra and penumbra of a sunspot.