Boron and Iron in AV 304: A B-dwarf in the SMC
Abstract
An upper limit in the boron abundance in AV 304 is determined as a test of cosmic ray spallation as the production of boron. Boron is determined from the B III resonance line at 2066 A from HST STIS data. AV 304 does not show signs of mixing or mass loss, which can destroy the fragile boron atom. The abundance othe boron seed nucleus, oxygen, is also well known in this star, and O is approximately the same from location to location in the SMC. Thus, the boron abundance from AV 304 should be representative of the abundance in ththe entire galaxy. We find an upper limit of 12+log(B/H)=1.7. This boron upper limit is lower than the oxygen depletion relative to the solar neighborhood by 0.3 dex. This is unlike the Galactic studies that suggest that boron scales linearly with oxygen. Additionally, the numerous Fe-group elements in the UV spectrum allows for a detailed Fe-group abundance determination. We find 12+log(Fe/H)=0.7+/-0.1, primarily from Fe III lines. The abundance is in excellent agreement with determinations from Fe I and Fe II lines in A-K supergiants in the SMC, and supports that O and Fe have the same underabundance in the SMC. We appreciate support for this project from NASA GO-08661, and Clare Boothe Luce research funds.
- Publication:
-
American Astronomical Society Meeting Abstracts #198
- Pub Date:
- November 2001
- Bibcode:
- 2001AAS...198.9303B