ULTRAVIOLET TRANSITIONS OF LOW CONDENSATION TEMPERATURE HEAVY-ELEMENTS AND NEW DATA FOR INTERSTELLAR ARSENIC, SELENIUM, TELLURIUM, AND LEAD

We report on the first interstellar detections of transitions of the h eavy elements As II and Se II along with 2 sigma upper limits for Te I I and Pb II. We also present a line list of the strongest ultraviolet transitions for an additional eight heavy elements, including rest wav elengths and a compilation of existing transition oscillator strengths along with new theoretical values for many species. All these transit ions fall within the accessible UV range of the Goddard High Resolutio n Spectrograph. With two exceptions, all these elements are characteri zed by relatively low condensation temperatures (T(c) less-than-or-equ al-to 720 K) and are therefore expected to be only lightly depleted on to dust. Because these elements are produced by a diverse mixture of s low and rapid neutron capture (s- and r-process), comparisons involvin g their measured abundances for different sight lines provide a unique probe of stellar evolution, nucleosynthetic enrichment, and the effic iency with which this material is mixed in the interstellar medium.