Boron in the Extreme Pop II Star HD 140283 and the Production of Light Elements in the Early Galaxy
B. Edvardsson, B. Gustafsson, S. G. Johansson, D. Kiselman, D. L. Lambert, P. E. Nissen, G. Gilmore
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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