Assigned ID: 499 ----- Submission 1 (Fri Jan 21 23:04:24 GMT 2005) ----- The complex history and evolution of element production is reflected in the abundance ratios of the elements. The distinctive abundance patterns produced by nucleosynthesis in supernovae and stars can be used to explore the history of star formation and evolution in galaxies. Recent observations of damped Lyman-alpha systems have suggested that observations of r- and s-process elements at high redshifts may soon provide a new window to explore chemical evolution. Paradoxically, we may soon have more detections of some elements in the interstellar medium of these high redshift galaxies than in the Galactic ISM. However, without an understanding of the depletion behavior of these elements based upon observations of nearby sight lines we may be unable to correctly disentangle the effects of dust depletion and nucleosynthesis. We therefore propose to mine the STScI Archive for spectra of sufficient resolution and signal-to-noise ratio to detect these rare elements and explore the implications of the results for the proportions of each element depleted into dust, the efficiency with which each is produced, and any variations in abundances, or their ratios to hydrogen or other elements, as functions of basic sight line properties.

ISM AND CIRCUMSTELLAR MATTER 12 75000 Budget for one year support. false 0.0 false false false false false SUPPORTED