The boron absorption line at 2089.6 AA in HD 140283

We have observed the B I line at 2089.6 AA in the metal poor star HD 140283 with HST/STIS. The observation was an attempt to confirm the B abundances derived from the 2497 AA B I line in earlier works in general, and for for this star in particular (Edvardsson et al. 1994 AA Kiselman & Carlsson 1996, A&A 311, 680). The resulting spectrum gained from 8 orbits of observations is hardly consistent with the boron abundance derived in the earlier works. A pure 10^B line could produce the feature observed but no reasonable process can produce such a ratio between 10^B and 11^B. 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 2497 AA line. We are proposing further observations to derive a more definite abundance from the line.