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A.M. Brooks, K.A. Venn (Macalester College), D.L. Lambert (U.Texas-Austin), M. Lemke (Bamberg), N. Langer (Utrecht)
We have used HST STIS spectra to determine boron and iron abundances in two well-studied B-stars. The boron abundances are used to search for evidence of rotational mixing while these stars are still on the main-sequence. New stellar evolution models (Heger et al. 2000) that include rotational mixing predict rapid depletion of boron from the surface before significant enrichments in nitrogen occur (both being affected by mixing with hotter gas from the H-burning layers). Examination of the new boron abundances, particularly with respect to nitrogen, suggest that rotation has affected the chemistry of one star, but not the other. In addition, we have calculated Fe-group abundances in these stars, which were previously unavailable, or highly uncertain, from optical spectroscopy.
The author(s) of this abstract have provided an email address for comments about the abstract: venn@clare.physics.macalester.edu