Heating the Quiet Corona by Explosive Events in UV: Results from “Sumer” on Board Soho

Abstract

We present SUMER observations of UV explosive events (EE) in a range which contains lines from about 750 to 790 Å. The strongest spectral lines of this range have temperatures of maximum abundances in the range 0.8 10⁵ - 6.3 10⁵ K and therefore are expected to be formed in the Transition Region (TR). The aim of this work is to investigate whether the EE originate in lines of a limited range of temperatures or indistinctly at lines of any temperature. We identified the times when the flux of a line attained the 3 and 5-σ levels. Moreover a considerably number of the events attained first a flux of 3 and 5-σ levels at a temperature of 1.5 10⁵ K. We interpret the above results as an indication that most of the EE could be originated in the intermediate layers of the TR.