A VAPID analysis of interstellar lithium in the ζ Oph sightline |
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| Authors: | Ian D Howarth Richard J Price Ian A Crawford Isabel Hawkins |
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| Institution: | Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT; Space Sciences Laboratory, University of California, Berkeley, CA 94720-7450, USA |
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| Abstract: | We present observations of the Li i 6708 Å doublet in the ζ Oph sightline, obtained at a resolution of ～106 and a signal-to-noise ratio of ～1200, together with supplementary observations of K i λ 7699 and the Na i λ 3302 doublet. These observations marginally resolve the main '?15 km s?1' system into its two principal clouds; we model the data using standard physical assumptions, but in a statistically rigorous manner, taking fully into account the hyperfine, doublet and isotopic structure for each species, in each cloud, using a new code, vapid . The average 7Li/6Li ratio determined in this sightline is 1.12±0.20 dex (68 per cent confidence interval), in excellent agreement with the solar-system (meteoritic) value. The ratios in the individual clouds are determined with less precision, but are also consistent with the solar-system value, as is the total lithium abundance (with little evidence for depletion). The thermal and 'turbulent' broadening in the two clouds is discussed on the basis of observed line widths. |
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| Keywords: | stars: individual: ζ Ophiuchi (HD 149757) ISM: atoms |
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