1998A&A...332.1017D

The Goddard High Resolution Spectrograph (GHRS) of the Hubble Space Telescope (HST) has been used to observe the boron 2500 Å region of BD -13 3442. At a metallicity of [Fe/H]=-3.00 this is the most metal-poor star ever observed for B. Nearly 26 hours of exposure time resulted in a detection. Spectrum synthesis using the latest Kurucz model atmospheres yields an LTE boron abundance of log ε(B)=+0.01±0.20. This value is consistent with the linear relation of slope ∼1.0 between log ε(B_LTE) and [Fe/H] found for 10 halo and disk stars by Duncan et al. (1997). Using the NLTE correction of Kiselman & Carlsson (1996), the NLTE boron abundance is log ε(B)=+0.93±0.20. This is also consistent with the NLTE relation determined by Duncan et al. (1997) where the slope of log ε(B_NLTE) vs. [Fe/H] is ∼0.7. These data support a model in which most production of B and Be comes from the spallation of energetic C and O nuclei onto protons and He nuclei, probably in the vicinity of massive supernovae in star-forming regions, rather than the spallation of cosmic ray protons and alpha particles onto CNO nuclei in the general interstellar medium.