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K. Cunha (UTEP/ON-CNPq), V. V. Smith (UTEP/McDonald Observatory)
We present the boron abundance for the Orion association G-dwarf member BD-06 1250 (Parenago 2339) derived from the B I 2497Å resonance lines. These spectra were obtained with the HST GHRS and represent the last data obtained with the GHRS, which failed while observing this star. Although only 1/3 of the planned spectra were obtained before the failure, an accurate B abundance could be derived. These observations are part of an ongoing program to probe boron in the young low-mass Orion association members. We derive a boron abundance of log (B/H) + 12. = 2.5 for BD-06 1250, which is roughly 0.2-0.3 dex below solar. The B abundance for this Orion G-dwarf is also lower, by about the same amount, in comparison to the boron abundances found for four Orion main-sequence B-stars. When these results are combined with the boron abundances derived from another Orion G-dwarf (BD-05 1317), as well as the ISM value into Orion, there is evidence for boron variation within the Orion association. Implications of such a variation will be discussed within the context of cosmic-ray fluxes and supernova neutrino induced nucleosynthesis.
The author(s) of this abstract have provided an email address for comments about the abstract: katia@baade.physics.utep.edu