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G. Sonneborn (NASA/GSFC), T. M. Tripp, E. B. Jenkins (Princeton U.), A. Vidal-Madjar, R. Ferlet (CNRS/IAP), U. J. Sofia (Whitman College), P. R. Wozniak (Princeton U.)
High resolution far ultraviolet spectra of the early-type stars \zeta Puppis, and \gamma2 Velorum were obtained with the Interstellar Medium Absorption Profile Spectrograph (IMAPS) during the 16-day ORFEUS-SPAS II mission in 1996 November. The IMAPS spectra cover the wavelength range ~930--1150Å\ with a spectral resolution of 4 km/sec (FWHM). High-quality spectra for these stars were obtained at Ly-\delta (949Å) and Ly-\epsilon (937Å) where the interstellar D I features are resolved, unsaturated, and cleanly separated from interstellar H I. The D I profiles were modeled using a velocity template derived from several N I lines in the IMAPS spectra. We minimized the \chi2 for model D I profiles that included not only the D I column density but also the effects of several sources of systematic error which were allowed to vary as free parameters. The analysis to date finds N(D I) =1.10 \times 1015 {\rm \,cm}-2 for \gamma2 Velorum and N(D I) =1.45 \times 1015 {\rm \,cm}-2 for \zeta Puppis. For N(H I) we used the same \chi2-minimization technique to analyze the Ly-\alpha absorption profiles in ~15 IUE SWP high dispersion spectra for each of these stars. We find N(H I) =5.18± 0.43 \times 1019 {\rm \,cm}-2 for \gamma2 Velorum and N(H I) =8.66±0.48 \times 1019 {\rm \,cm}-2 for \zeta Puppis. This yields D/H =2.12 \times 10-5 for \gamma2 Velorum and 1.67 \times 10-5 for \zeta Puppis. An evaluation of the errors and uncertainties will be presented.