2002ApJS..140...51S

High-resolution far-UV spectra of the O-type subdwarf BD +28°4211 were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) to measure the interstellar deuterium, nitrogen, and oxygen abundances in this direction. The interstellar D I transitions are analyzed down to Lyι at 920.7 Å. The star was observed several times at different target offsets in the direction of spectral dispersion. The aligned and co-added spectra have high signal-to-noise ratios (S/N=50-100). D I, N I, and O I transitions were analyzed with curve-of-growth and profile fitting techniques. A model of interstellar molecular hydrogen on the line of sight was derived from H₂ lines in the FUSE spectra and used to help analyze some features where blending with H₂ was significant. The H I column density was determined from high-resolution Hubble Space Telescope Space Telescope Imaging Spectrograph spectra of Lyα to be logN(HI)=19.846±0.035 (2 σ), which is higher than is typical for sight lines in the local interstellar medium (ISM) studied for D/H. We found that D/H=(1.39±0.21)x10^–5 (2 σ) and O/H=(2.37±0.55)x10^–4 (2 σ). O/H toward BD +28°4211 appears to be significantly below the mean O/H ratio for the ISM and the Local Bubble.