A Survey of Interstellar Sulfur Abundance and Implications for P II Oscillator Strengths

Abstract

A study of interstellar gas-phase S abundance is presented which is based mainly on abundances for 39 sight lines newly derived from recently published Copernicus UV absorption-line measurements and archival IUE data. A trend of increasing depletion with increasing mean H volume density n-bar(H) is evident which is similar to that already established for another volatile element, Cl, but weaker than the dependence of depletion on n-bar(H) exhibited by refractory elements such as Ca, Ti, and Mg. The results confirm that S is not a major constituent of interstellar grains. A comparison of Doppler widths derived for S II and P II in the same sight lines reveals an unexpected systematic discrepancy of a factor of about 1.7.