Boron in the Extreme Pop II Star HD 140283 and the Production of Light Elements in the Early Galaxy
Abstract
Using observations of the 2496.7 A B I line with the HST GHRS at a nominal resolution of 90,000, we have found the abundance of boron of HD 140283 to be log epsilonB (= 12 + log (NB/NH)) = 0.34 0.20. This result is found when a significant non-LTE effect in the formation of the B I line is taken into account. The resulting NB/NBe ratio is about 17 (in the range 9 -- 34), which is in very good agreement with what is expected from spallation by cosmic rays. We conclude that this origin of Be and B in the Early Galaxy is the most probable of recently suggested formation mechanisms. (Submitted to A&A. Postscript figures available via annymous ftp to "chiron.astro.uu.se" in directory pub/Preprints/P87)
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