Interstellar abundances toward zeta Ophiuchi

Extensive Copernicus observations of interstellar absorption lines in front of zeta Oph have been combined with similar ground-based data to give column densities or limits on 26 elements in H I clouds. Compared with solar-system abundances, there is a depletion of most elements relative to hydrogen, except S and Zn, by factors of 3 to 4000. The depletions generally are larger for the higher condensation temperatures.