The depletion of interstellar gaseous iron

The Copernicus UV telescope was used to measure equivalent widths of interstellar Fe II resonance lines toward 55 early-type stars; the measurements permit the determination of Fe II column densities. The depletion of interstellar gaseous iron was obtained by combining these measurements with the results from a previous atomic and molecular hydrogen survey program; the derived depletions refer mostly to matter in H I regions. As an example, the nearly normal gaseous iron abundance in the distant high-latitude intermediate-velocity cloud toward HD 93521 is consistent with the idea that these clouds are produced by galactic supernova explosions.