Observing Boron in Metal-Poor Stars |
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| Authors: | F Primas |
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| Institution: | (1) European Southern Observatory, Karl Schwarzschild str. 1, D-85748 Garching München, Germany |
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| Abstract: | A new sample of 7 stars ranging in metallicity from Fe/H] = −2.0 to Fe/H] = −0.75 has been analyzed in the boron spectral
region. The targets were selected according to the availability (in the literature) of their lithium and beryllium abundances,
because the simultaneous knowledge of LiBeB in the same targets is a powerful diagnostic for testing depletion and internal
mixing predicted by different stellar structure models. Two stars (HD 94028 and HD 194598), characterized by similar Li contents,
are found to have also similar B abundances, despite a 0.3 dex difference in their Be abundances claimed by Thorburn and Hobbs
(1996). Four stars out of 7 are characterized by strongly depleted Li and Be abundances: 2 of them (HD 2665 and HD 3795) are
also significantly B-depleted, while two others (HD 106516 and HD 221377) have near normal B abundances despite being depleted
by a factor ≥ 10 in both Li and Be abundances. These stars place strong constraints on the nature and depth of the mixing
processes responsible for their light element abundances. The 7th star (HD 160617) shows the remarkable aspect of deficient
B, probably deficient Be, and completely normal Li. No stellar destruction mechanism can explain this. Rather, chemical inhomogeneities
in the halo could be the cause.
This revised version was published online in July 2006 with corrections to the Cover Date. |
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