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Deuterium Abundance Toward G191-B2B: Results from the Far Ultraviolet Spectroscopic Explorer (FUSE) MissionHigh-resolution spectra of the hot white dwarf G191-B2B covering the wavelength region 905-1187A were obtained with the Far Ultraviolet Spectroscopic Explorer (FUSE). This data was used in conjunction with existing high-resolution Hubble Space Telescope STIS observations to evaluate the total H(sub I), D(sub I), O(sub I) and N(sub I) column densities along the line of sight. Previous determinations of N(D(sub I)) based upon GHRS (Goddard High Resolution Spectrograph) and STIS (Space Telescope Imaging Spectrograph) observations were controversial due to the saturated strength of the D(sub I) Lyman alpha line. In the present analysis the column density of D(sub I) has been measured using only the unsaturated Lyman beta and Lyman gamma 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 character series has been performed. The column densities derived are: log N(D(sub I)) = 13.40+/-0.07, log N(O(sub I)) = 14.86+/-0.07, and log N(N(sub I)) = 13.87+/-0.07 quoted with 2sigma, uncertainties. The measurement of the H(sub I) column density by profile fitting of the Lyman alpha line has been found to be unsecure. If additional weak hot interstellar components are added to the three detected clouds along the line of sight, the H(sub I)) column density can be reduced quite significantly, even though the signal-to-noise ratio and spectral resolution at Lyman alpha are excellent. The new estimate of N(H(sub I)) toward G191-B2B reads: logN(H (sub I)) = 18.18+/-0.18 (2sigma uncertainty), so that the average (D/H) ratio on the line of sight is: (D/H)= 1.66(+0.9/-0.6) x 10(exp -5) (2sigma uncertainty).
Document ID
20020068547
Acquisition Source
Goddard Space Flight Center
Document Type
Preprint (Draft being sent to journal)
Authors
Lemoine, M. (Institut d'Astrophysique Paris, France)
Vidal-Madjar, A. (Institut d'Astrophysique Paris, France)
Hebrard, G. (Institut d'Astrophysique Paris, France)
Desert, J.-M. (Institut d'Astrophysique Paris, France)
Ferlet, R. (Institut d'Astrophysique Paris, France)
LecavelierdesEtangs, A. (Institut d'Astrophysique Paris, France)
Howk, J. C. (Johns Hopkins Univ. Baltimore, MD United States)
Andre, M. (Johns Hopkins Univ. Baltimore, MD United States)
Blair, W. P. (Johns Hopkins Univ. Baltimore, MD United States)
Friedman, S. D. (Johns Hopkins Univ. Baltimore, MD United States)
Oegerle, William R.
Date Acquired
September 7, 2013
Publication Date
January 1, 2002
Subject Category
Astrophysics
Funding Number(s)
CONTRACT_GRANT: NAS5-32985
Distribution Limits
Public
Copyright
Work of the US Gov. Public Use Permitted.

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