2000A&A...363L..33T

We have observed the Bi line at 2089.6Å in the metal poor star HD 140283 with HST/STIS. The observation was an attempt to confirm the B abundances derived from the 2497Å Bi line in earlier works in general, and for for this star in particular (Edvardsson et al., 1994A&A...290..176E; Kiselman & Carlsson, 1996A&A...311..680K). The resulting spectrum gained from 8 orbits of observations is hardly consistent with the boron abundance derived in the earlier works. A pure ¹⁰B line could produce the feature observed but no reasonable process can produce such a ratio between ¹⁰B and ¹¹B. More likely the analysed feature is affected by a statistical fluctuation. A conservative upper limit estimate of the NLTE corrected boron abundance gives a value marginally consistent with that derived from the 2497Å line. We are proposing further observations to derive a more definite abundance from the line.