Boron in the extreme Pop II star HD 140283 and the production of light elements in the Early Galaxy ⋆

Using observations of the 2496.7 Å B i line with the HST GHRS at a nominal resolution of 90,000, we have found the abundance of boron of HD140283 to be log ǫB(= 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.