Limits on the boron isotopic ratio in HD 76932

Data in the lambda 2090 B region of HD 76932 have been obtained at a high s ignal-to-noise ratio using the Hubble Space Telescope Goddard High-Resoluti on Spectrograph echelle at a resolution of 90,000. This wavelength region h as been previously identified as a likely candidate for observing the B-11/ B-10 isotopic splitting. The observations do not match a calculated line pr ofile extremely well at any abundance for any isotopic ratio. If the B abun dance previously determined from observations at lambda 2500 is assumed, th e calculated line profile is too weak, indicating a possible blending line. Assuming that the absorption at lambda 2090 is entirely due to boron, the best-fit total B abundance is higher than, but consistent with, that obtain ed at lambda 2500, and the best-fit isotopic ratio (B-11/B-10) is in the ra nge similar to 10:1 to similar to 4:1. If the absorption is not entirely du e to B and there is an unknown blend, the best-fit isotopic ratio may be cl oser to 1:1. Future observations of a similar metal-poor star known to have unusually low B should allow us to distinguish between these two possibili ties. The constraints that can be placed on the isotopic ratio based on com parisons with similar observations of HD 102870 and HD 61421 (Procyon) are also discussed.