A long-lived coronal arch system observed in X-rays

A large long-lived soft X-ray emitting arch system was observed during the last Skylab mission. This arcade stayed in the same approximate position for several solar rotations. It is suggested that these long-lived arches owe their stability to the stable coronal magnetic-field configuration. A global constant-alpha force-free magnetic-field analysis, as developed by Nakagawa et al. (1977), is used to describe the arches, and results in a marked resemblance between the theoretical magnetic-field configuration and the observed X-ray emitting feature.