Heavy Element Abundances in AV 304, a B0.5 Main Sequence Star in the Small Magellanic Cloud
Abstract
We propose HST/GHRS of AV 304, a sharp-lined B0.5 main sequence star in the Small Magellanic Cloud, to determine the abundances of heavy elements, especially those of the iron group. For this exploratory study, we have selected three spectral fields {using the G160M grating} that contain measurable features of Ti III, V III, Cr III, Mn III, and Fe III, as well as prominent lines of C III, Si II, III, and S II. An analysis of ground-based data of this 15th magnitude star by Dufton, et al. {1990} revealed an average underabundance of 0.7 dex for most light elements, but a normal He abundance. This will be the first attempt to measure the abundances of Fe group elements in the photosphere of an early B, main sequence star in an external galaxy. Although abundances of the Fe-peak elements are of interest because they are important for assessing opacities for stellar evolution calculations and the validity of theoretical calculations of explosive nucleosynthesis, the above-mentioned study did not yield this information because measurable lines from these species are found only in the UV spectral region. Abundances and abundance ratios of both heavy & light elements will be compared with results from H II regions, supernova remnants, and evolved massive stars in the SMC and theoretical calculations of nucleosynthesis.
- Publication:
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HST Proposal
- Pub Date:
- July 1997
- Bibcode:
- 1997hst..prop.7759P