0 Assigned ID: 92 ----- Attempting Submission 1 (Tue Apr 05 01:30:49 GMT 2016) ----- Previous HST observations of UV interstellar absorption features in stellar spectra have revealed that the abundance of free krypton atoms relative to hydrogen in the interstellar medium of the Milky Way is below estimates for the solar abundance ratio of Kr by about 0.3 dex. This seems puzzling in view of the fact that Kr is usually regarded as chemically inert, and its van der Waals binding to neutral partners is extremely weak. In order to identify the most likely mechanism for depleting Kr, a study of Kr I column densities over a large and diverse collection of sight lines may reveal possible relationships of Kr deficiencies with either molecular hydrogen fractions or depletions of other elements by dust formation. The outcome should help to establish the plausibility that free Kr atoms are removed from the gas phase either by the formation of KrH^+ or KrH_3^+, or alternatively, by the trapping of Kr atoms into water ice clathrates on or within dust grains. The objective of this archival research is to retrieve and analyze the STIS E140H and E140M spectra of 79 (or possibly more) stars that have not been studied earlier, in order to measure the column densities of Kr I, Mg II, Mn II, Ge II, and H I. For sight lines with no published values for molecular hydrogen column densities, FUSE spectra will also be downloaded and analyzed. Stellar Physics 0 Regular false true false SUPPORTED