The intensities and profiles of XUV transition zone lines in a quiet sun region compared to a polar coronal hole

The intensities of XUV transition-zone lines from limb spectra of a quiet-sun region and a polar coronal hole are compared. The spectra were obtained with a slit spectrograph on Skylab and cover a region from -12 sec within the limb to 20 sec above it. The lines selected for comparison are formed at temperatures that range from 36,000 to 220,000 K. Lines of the higher-temperature ions, e.g. O v, are significantly less intense in the coronal hole, and lines of lower-temperature ions show little change. Profiles of selected optically thin transition-zone lines from the quiet-sun and coronal-hole spectra are also shown. The lines are broader than expected in ionization equilibrium, and bulk-motion velocities are deduced from the widths of the lines. There appears to be little, if any, statistically significant difference in the velocities obtained from the quiet-sun region and the coronal hole.