Far-Ultraviolet Observations of the Loop I/North Polar Spur Region

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.