Statistical comparison of transition region blinkers and explosive events

Abstract

Explosive events and blinkers are two observational classes of transients seen on the quiet Sun and an investigation of the significance of and relationship between such events may be critical for understanding basic processes at work in the solar atmosphere. We analysed five time-series spectra of the quiet Sun of transition region O XV 629 Å, O XVI 1032 Å and O XVI 1038 Å lines. We investigated how often explosive events occurred during the course of a blinker at the same location and found that slightly more than a half of all explosive events happened during about one third of all blinkers. In some cases during a blinker more than one explosive event was registered. The largest average maximum relative intensity enhancement was for blinkers with explosive events, followed by the blinkers without explosive events, with the least being for the explosive events which did not happen during the course of a blinker. Due to these differences among the maximum enhancements between these events we suppose that blinkers and explosive events are two independent phenomena. Intensity light curves of blinkers show that events can be separated into two classes, specifically: 1) simple blinkers with smooth increase in intensity having only one significant peak, and 2) complex blinkers characterised by multiple (2-4) significant peaks. These two classes were equally represented when frequencies of their occurrences were averaged over five analysed data-sets. The analysis of the line profile parameters and their correlations for these two classes did not give any result which could further distinguish between them. During blinkers the intensity peaks mostly at the middle of their durations, while the line width peaks somewhat earlier than the intensity. This was a general character for both simple and complex blinkers, as well as for all explosive events.