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A. Vidal-Madjar, M. Lemoine, G. Hébrard, J.-M. Désert, R. Ferlet, A. Lecavelier des Etangs (CNRS/IAP), M. André, W.P. Blair, S.D. Friedman, J.C. Howk, J.W. Kruk, H.W. Moos, W.R. Oegerle, K.R. Sembach (JHU), P. Chayer (UVIC/JHU), G. Sonneborn (NASA/GSFC), FUSE Science Team
High-resolution spectra of the hot white dwarf G191-B2B were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). By combining the 905--1187\,Å\ FUSE datawith existing high-resolution observations made with both the GHRS and the STIS instruments on board the Hubble Space Telescope, it was possible to evaluate simultaneously the average H\,{\sc i}, D\,{\sc i}, O\,{\sc i}, and N\,{\sc i} column densities for the sight line. Because previous evaluations of N(D\,{\sc i}) based upon GHRS and STIS observations were controversial due to the great strength of the D\,{\sc i} Lyman~\alpha line, the present deuterium evaluation was made solely from the FUSE data at Lyman~\beta and Lyman~\gamma.
In the course of this analysis, many possible systematic errors were investigated. Some systematic errors, such as fixed-pattern noise and background uncertainties, were reduced considerably by using data from the several different FUSE channels. Others, such as continuum placement and the number of components adopted for the velocity component model, were minimized by evaluating the interstellar line strengths using both weak and strong lines as well as simultaneously fitting the FUSE and STIS high resolution observations. We will discuss our analysis of this sight line and the resulting D/H, D/O and D/N evaluations for the various components, including values for the Local Interstellar Cloud in which the Solar System is embedded.
This work is based on data obtained for the Guaranteed Time Team by the NASA-CNES-CSA FUSE mission operated by the Johns Hopkins University. Financial support to U. S. participants has been provided by NASA contract NAS5-32985.
The author(s) of this abstract have provided an email address for comments about the abstract: alfred@iap.fr