Deuterated molecular hydrogen in the Galactic ISM. New observations along seven translucent sightlines - Université Pierre et Marie Curie Accéder directement au contenu
Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2005

Deuterated molecular hydrogen in the Galactic ISM. New observations along seven translucent sightlines

Résumé

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 Ultraviolet Spectroscopic Explorer (FUSE). The other ten values are from a reanalysis of spectra obtained with Copernicus. In all cases, high-resolution ground-based observations of K I and/or the CH molecule were used to constrain the gas velocity structure and to correct for saturation effects. Comparisons of the column densities HD, CH, CN, and K I in these 17 sightlines indicate that HD is most tightly correlated with CH. Stringent lower limits to the interstellar D/H ratio, derived from the HD/2H2 ratio, range from 3.7 × 10-7 to 4.3 × 10-6. Our results also suggest that the HD/H2 ratio increases with the molecular fraction f(H2) and that the interstellar D/H ratio might be obtained from HD by probing clouds with f(H2) ˜ 1. Finally, we note an apparent relationship between the molecular fractions of hydrogen and deuterium.

Dates et versions

hal-03732705 , version 1 (21-07-2022)

Identifiants

Citer

Sylvestre Lacour, Michel André, Paule Sonnentrucker, Franck Le Petit, D. E. Welty, et al.. Deuterated molecular hydrogen in the Galactic ISM. New observations along seven translucent sightlines. Astronomy and Astrophysics - A&A, 2005, 430, pp.967-977. ⟨10.1051/0004-6361:20041589⟩. ⟨hal-03732705⟩
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