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| Paper: |
Interstellar deuterium abundance on the distant line of sight of HD90087 |
| Volume: |
348, Astrophysics in the Far Ultraviolet: Five Years of Discovery with FUSE |
| Page: |
82 |
| Authors: |
Hebrard, G.; Chayer, P.; Dupuis, J.; Moos, H.W.; Sonnentrucker, P.; Tripp, T.M.; Williger, G.M. |
| Abstract: |
We present a deuterium abundance study on the sight line to the O star HD90087, located 2.7 kpc away from the Sun in the Galactic disk. The FUSE spectra show numerous blended interstellar and stellar features. Our analysis reduced the statistical and systematic errors by fitting the unsaturated interstellar absorption lines simultaneously to determine column densities. The hydrogen column density was measured by fitting the wings of the Ly α line, in IUE spectra. We report low ratios: D/O = (1.7 ± 0.7) × 10−2, D/N = (1.1 ± 0.4) × 10−1, and D/H = (9.8 ± 38) × 10−6 (2 σ).
Both in terms of distance and column densities, HD90087 is the farthest target for which deuterium has been measured from ultraviolet absorption lines in the Galactic disk. Thus, many interstellar clouds are probed along this sight line. This should average out possible variations in the properties of individual clouds and yield a value for the interstellar deuterium abundance, that is representative of the local Milky Way at the present epoch. Previous FUSE results on distant targets suggested that the present-epoch deuterium abundance (D/H)PE might be two times lower than the one measured in the local interstellar medium. Our results reinforce this conclusion and favor (D/H)PE = (7 ± 2) × 10−6. |
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