Far-ultraviolet observations of the Loop I/North Polar Spur region

Abstract

The results of diffuse far-.ultraviolet observations of the Loop I/ North Polar Spur ( NPS) region are presented in this Letter. Several important ionic emission lines, including C iv, Si II*, Si iv, and Al II, were detected. Fluorescent emission lines from hydrogen molecules were also seen in the spectra. A spectral image made with C iv emission shows a shell- like feature colocated with the X- ray NPS. This feature is located just inside the Loop I radio ridges. Another interesting C iv feature is seen at the inner edge of the " interaction ring," where the cold interstellar medium is in direct contact with the X- ray - bright hot gas. The present observation is in good agreement with a model of recent supernova explosion in an inhomogeneous medium, possibly disturbed by previous multiple supernova explosions.