Giant solar arches and coronal mass ejections in November 1980

Abstract

Using data from the SOLWIND coronagraph and photometers aboard HELIOS-A we examine coronal mass ejections from an active region which produced a series of giant post-flare coronal arches. HXIS X-ray observations reveal that in several cases underlying flares did not disrupt these arch structures, but simply revived them, enhancing their temperature, density and brightness. Thus we are curious to know how these quasi-stationary X-ray structures could survive in the corona in spite of recurrent appearances of powerful dynamic flares below them. We have found reliable evidence that two dynamic flares which clearly revived the preexisting giant arch were not associated with any mass ejection. After two other flares, which were associated with mass ejections, the arch might have been newly formed when the ejection was over. In one of these cases, however, the arch had typical characteristics of a revived structure so that it is likely that it survived a powerful mass ejection nearby. In a magnetic configuration of the arch which results from potential-field modelling (Figure 1(b)) such a survival seems possible.