Boron is a trace element in hot stars which can be observed from the B II resonance line at 1362 Angstroms. We have used IUE archival spectra to examine the B abundances in early type stars. The abundances of boron in A and B-type stars were originally calculated by Boesgaard & Heacox (1978 ApJ 226, 888) from Copernicus spectra as a method of testing the predictions of galactic cosmic ray spallation reactions. We are primarily interested in the effects of stellar evolution on B. Boesgaard & Heacox do not report any relationship between evolutionary state and the B abundance, however there are very few evolved stars in their sample and the few studied have very large uncertainties in B. Boron is destroyed by protons at temperatures above about 4 million K, thus the stellar surface B abundance is a sensitive monitor of evolutionary processes, such as mass loss and mixing, which would lead to large losses in the surface B. Gies & Lambert (1992 ApJ 387, 673) found evidence of CNO-cycled gas in some slightly evolved B-type stars, suggesting that some mixing may occur in massive stars near the main-sequence. We examine the B abundances in these stars for evidence of a boron-nitrogen relationship.
American Astronomical Society Meeting Abstracts #184
- Pub Date:
- May 1994