Crawford, Ian (1992) High-resolution observations of the interstellar NaI UV doublet and a discussion of the resulting NaI/CaII ratios. Monthly Notices of the Royal Astronomical Society 259 (1), pp. 47-62. ISSN 0035-8711.
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Abstract
High-resolution (6 km s−1 FWHM) observations of the interstellar λ3302 Na I doublet towards 11 southern early-type stars are presented. The analysis has resulted in much more accurate Na I column densities than those obtained from earlier studies of the (fully saturated) Na D lines. The λ3302 lines have low radial velocities (−15 ≲ υlsr ≲ + 10 km s−1) and are much simpler than the Na D and Ca II profiles towards the same stars, generally occurring at those velocities previously identified with diffuse molecular clouds. Analysis of the Na I/Ca II ratios in these components indicates that δCa ≈ −3 to −4 in the molecular clouds, implying that most of the Ca has been adsorbed on to the surfaces of interstellar grains. Lower Ca depletions are found in the less dense (non-molecular) clouds which are responsible for the additional absorption observed in the Na D and Ca K lines at both high and low velocities.
Metadata
| Item Type: | Article |
|---|---|
| School: | Birkbeck Faculties and Schools > Faculty of Science > School of Natural Sciences |
| Depositing User: | Sarah Hall |
| Date Deposited: | 19 Aug 2019 13:49 |
| Last Modified: | 02 Aug 2023 17:53 |
| URI: | https://eprints.bbk.ac.uk/id/eprint/28633 |
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