Deuterium Abundance toward G191-B2B: Results from the FUSE Mission

High-resolution spectra of the hot white dwarf G191-B2B, covering the wavelength region 905-1187 Å, were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). These data were used in conjunction with existing high-resolution Hubble Space Telescope Space Telescope Imaging Spectrograph (STIS) observations to evaluate the total H I, D I, O I, and N I column densities along the line of sight. Previous determinations of N(D I) based upon GHRS and STIS observations were controversial as a result of the saturated strength of the D I Lyα line. In the present analysis the column density of D I has been measured using only the unsaturated Lyβ and Lyγ lines observed by FUSE. A careful inspection of possible systematic uncertainties tied to the modeling of the stellar continuum or to the uncertainties in the FUSE instrumental characteristics has been performed. The column densities derived are log N(D ) = 13.40 ± 0.07, log N(O ) = 14.86 ± 0.07, and log N(N ) = 13.87 ± 0.07, quoted with 2 σ uncertainties. The measurement of the H I column density by profile fitting of the Lyα line has been found to be uncertain. If additional weak, hot interstellar components are added to the three detected clouds along the line of sight, the H I column density can be reduced quite significantly, even though the signal-to-noise ratio and spectral resolution at Lyα are excellent. The new estimate of N(H I) toward G191-B2B reads log N(H ) = 18.18 ± 0.18 (2 σ), so that the average D/H ratio on the line of sight is D/H = × 10-5 (2 σ).

[1]  S. Lacour,et al.  Deuterium Abundance toward WD 2211–495: Results from the FUSE Mission , 2002 .

[2]  A. Vidal-Madjar,et al.  Deuterium Abundance toward WD 1634–573: Results from the FUSE Mission , 2002 .

[3]  G. Hébrard,et al.  Deuterium Abundance toward WD 0621–376: Results from the FUSE Mission , 2002 .

[4]  Abundances of Deuterium, Nitrogen, and Oxygen toward HZ 43A: Results from the FUSE Mission , 2002, astro-ph/0201298.

[5]  A. Vidal-Madjar D/h measurements , 2001, astro-ph/0103170.

[6]  J. Thorstensen,et al.  Hubble Space Telescope Imaging Spectrograph Observations of the Hot White Dwarf in the Close Binary Feige 24 , 2000 .

[7]  G. Zank,et al.  Hydrogen Lyα Absorption Predictions by Boltzmann Models of the Heliosphere , 2000, astro-ph/0007171.

[8]  F. Spite The Light Elements: What is Known, What is Controversial , 2000 .

[9]  M. Spite,et al.  The Light Elements and their Evolution , 2000 .

[10]  J. Howk,et al.  Background and Scattered-Light Subtraction in the High-Resolution Echelle Modes of the Space Telescope Imaging Spectrograph , 1999, astro-ph/9912388.

[11]  D. York,et al.  Deuterium abundances , 1999, astro-ph/9903043.

[12]  G. Sonneborn,et al.  Spatial Variability in the Ratio of Interstellar Atomic Deuterium to Hydrogen. II. Observations toward γ2 Velorum and ζ Puppis by the Interstellar Medium Absorption Profile Spectrograph , 1999, astro-ph/9901403.

[13]  M. Barstow,et al.  An alternative explanation of the EUV spectrum of the white dwarf G191-B2B invoking a stratified H+He envelope including heavier elements , 1998 .

[14]  Martin A. Barstow,et al.  The effect of photospheric heavy elements on the hot DA white dwarf temperature scale , 1998 .

[15]  Stuart Bowyer,et al.  Properties of the Hot DA White Dwarf HZ 43 Based on Far-Ultraviolet ORFEUS-SPAS II Observations , 1998 .

[16]  C. Chiappini,et al.  Is High Primordial Deuterium Consistent with Galactic Evolution? , 1997, astro-ph/9706114.

[17]  M. Lemke,et al.  Extended VCS Stark broadening tables for hydrogen – Lyman to Brackett series , 1997 .

[18]  F. Timmes,et al.  Light-Element Abundances from z = 0 to z = 5 , 1997, astro-ph/9701243.

[19]  K. Olive,et al.  The Effects of an Early Galactic Wind on the Evolution of D,3He, and Z , 1996, astro-ph/9607106.

[20]  Martin A. Barstow,et al.  A Self-Consistent Optical, Ultraviolet, and Extreme-Ultraviolet Model for the Spectrum of the Hot White Dwarf G191-B2B , 1996 .

[21]  S. Bowyer,et al.  Discovery of Photospheric Sulfur and Phosphorus in ORFEUS Spectra of the Hot White Dwarfs G191-B2B and MCT O455-2812 , 1996 .

[22]  Stuart Bowyer,et al.  Hot White Dwarfs in the Local Interstellar Medium: Hydrogen and Helium Interstellar Column Densities and Stellar Effective Temperatures from Extreme-Ultraviolet Explorer Spectroscopy , 1995 .

[23]  D. Koester,et al.  The remarkably low abundance of helium in the atmosphere of the DA white dwarf HZ43 , 1995 .

[24]  M. Cassé,et al.  Cosmological and Astrophysical Consequences of a High Primordial Deuterium Abundance , 1995 .

[25]  Ivan Hubeny,et al.  Non-LTE line-blanketed model atmospheres of hot stars. 1: Hybrid complete linearization/accelerated lambda iteration method , 1995 .

[26]  K. Olive,et al.  On the Galactic Evolution of $D$ and $^3He$ , 1993, astro-ph/9310021.

[27]  M. Allen,et al.  Interstellar absorption along the line of sight to theta Carinae using Copernicus observations , 1992 .

[28]  R. Terlevich,et al.  The Primordial helium abundance from observations of extragalactic H-II regions , 1992 .

[29]  G. Steigman,et al.  Big bang nucleosynthesis , 1985 .

[30]  T. Owen,et al.  Cosmological implications of helium and deuterium abundances on Jupiter and Saturn , 1983, Nature.

[31]  D. York The interstellar medium near the sun. III - Detailed analysis of the line of sight to lambda Scorpii , 1983 .

[32]  D. York,et al.  The interstellar medium on the Gamma Cassiopeiae line of sight , 1980 .

[33]  F. Wesemael,et al.  Atmospheres for hot, high-gravity stars. I. Pure hydrogen models. , 1980 .

[34]  D. York,et al.  The ratio of deuterium to hydrogen in interstellar space. IV. The lines of sight to delta , epsilon , and iota Orionis. , 1979 .

[35]  D. York,et al.  Implications of high-velocity interstellar H I absorption features , 1979 .

[36]  D. York,et al.  The ratio of deuterium to hydrogen in interstellar space. III - The lines of sight to Zeta Puppis and Gamma Cassiopeiae , 1977 .

[37]  D. York,et al.  The abundance of deuterium relative to hydrogen in interstellar space , 1976 .

[38]  B. Tinsley,et al.  Chemical Evolution of Galaxies , 1976 .

[39]  D. York,et al.  Interstellar deuterium abundance in the direction of beta Centauri , 1973 .

[40]  J. Cooper,et al.  Hydrogen Stark-Broadening Tables , 1973 .