Related papers: Hydrogen column density evaluations toward Capella…
An accurate value of the deuterium/hydrogen (D/H) ratio in the local interstellar medium (LISM) and a better understanding of the D/H variations with position in the Galactic disk can provide essential information on the primordial D/H…
We present high S/N measurements of the H I Ly alpha absorption line toward 16 Galactic targets which are at distances between approximately 190 and 2200 pc, all beyond the wall of the Local Bubble. We describe the models used to remove…
We present column density measurements of the HD molecule in the interstellar gas toward 17 Galactic stars. The values for the seven most heavily reddened sightlines, with E(B-V) = 0.38-0.72, are derived from observations with the Far…
Because the ionization balances for HI, OI, and DI are locked together by charge exchange, D/O is an important tracer for the value of the D/H ratio and for potential spatial variations in the ratio. As the DI and OI column densities are of…
To measure interstellar atomic deuterium abundances, we used the Interstellar Medium Absorption Profile Spectrograph (IMAPS) to obtain spectra of gamma2 Vel and zeta Pup over the wavelength interval 930-1150 A at a resolving power of…
We present constraints on the deuterium to hydrogen ratio (D/H) in the metal-poor gas cloud at redshift $z=0.701$ towards QSO 1718+4807. We use new Keck spectra in addition to Hubble Space Telescope (HST) and International Ultraviolet…
We present measurements of the column densities of interstellar DI, OI, NI, and H2 made with FUSE, and of HI made with IUE toward the sdO star LSE 44, at a distance of 554+/-66 pc. This target is among the seven most distant Galactic sight…
We present high spectral resolution HST-GHRS observations of the white dwarf G191-B2B, and derive the interstellar D/H ratio on the line of sight. We have observed and analysed simultaneously the interstellar lines of HI, DI, NI, OI, SiII,…
Observations show that the global deuterium-to-hydrogen ratio (D/H) in the local interstellar medium (ISM) is about 90% of the primordial ratio predicted by big bang nucleosynthesis. The high (D/H)$_{ISM}$ implies that only a small fraction…
We use high resolution spectra obtained with FUSE and STIS to obtain interstellar column densities of H I, D I, O I, S II, Fe II and P II toward the QSO HE 0226-4110 ( l = 253.4 deg , b = -65.77 deg). We obtain D/H = 21(+8, -6) ppm.…
Current measurements indicate that the deuterium abundance in diffuse interstellar gas varies spatially by a factor of ~4 among sightlines extending beyond the Local Bubble. One plausible explanation for the scatter is the variable…
As the Galaxy evolves, the abundance of deuterium in the interstellar medium (ISM) decreases from its primordial value: deuterium is "astrated". The deuterium astration factor, f_D, the ratio of the primordial D abundance (the D to H ratio…
The primordial abundance of deuterium (D/H) yields a measure of the density of baryons in the universe and is an important complement to determinations from cosmic microwave background (CMB) experiments. Indeed, the current small sample of…
Studies of the abundances of deuterium in different astrophysical sites are of fundamental importance to answering the question about how much deuterium was produced during big bang nucleosynthesis and what fraction of it was destroyed…
Observations obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) have been used to determine the column densities of D I, O I, and N I along seven sight lines that probe the local interstellar medium (LISM) at distances from 37…
We determine the D/H ratio in the interstellar medium toward the DO white dwarf PG0038+199 using spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE), with ground-based support from Keck HIRES. We employ curve of growth, apparent…
Analyses of spectra obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE) satellite, together with spectra from the Copernicus and IMAPS instruments, reveal an unexplained very wide range in the observed deuterium/hydrogen (D/H)…
Recent HST/GHRS observations of the z = 0.7010 absorber toward the QSO 1718+4807 (selected because of apparently ideal characteristics for measuring D/H) yield a D/H significantly higher D/H than some recent high-redshift measurements. Our…
We report the measurement of the primordial D/H abundance ratio towards QSO \object. The column density of the hydrogen in the $z \simeq 2.536$ Lyman limit system is high, \lnhi $= 19.422 \pm 0.009$ \cmm, allowing for the deuterium to be…
We use new FUSE data to determine the column densities of interstellar DI, NI, OI, FeII, and H2 along the HD41161 and HD53975 sightlines. Together with N(HI) from the literature (derived from Copernicus and IUE data) we derive D/H, N/H, and…