Surface abundances of light elements for a large sample of early B-type stars – IV. The magnesium abundance in 52 stars – a test of metallicity |
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| Authors: | L S Lyubimkov S I Rostopchin T M Rachkovskaya D B Poklad D L Lambert |
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| Institution: | Crimean Astrophysical Observatory, Nauchny, Crimea, Ukraine, 98409;Department of Astronomy, University of Texas at Austin, RLM 15.308, USA, TX 78712 |
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| Abstract: | From high-resolution spectra a non-local thermodynamic equilibrium analysis of the Mg ii 4481.2-Å feature is implemented for 52 early and medium local B stars on the main sequence (MS). The influence of the neighbouring line Al iii 4479.9-Å is considered. The magnesium abundance is determined; it is found that log ?(Mg) = 7.67 ± 0.21 on average. It is shown that uncertainties in the microturbulent parameter Vt are the main source of errors in log ?(Mg) . When using 36 stars with the most reliable Vt values derived from O ii and N ii lines, we obtain the mean abundance log ?(Mg) = 7.59 ± 0.15 . The latter value is precisely confirmed for several hot B stars from an analysis of the Mg ii 7877-Å weak line. The derived abundance log ?(Mg) = 7.59 ± 0.15 is in excellent agreement with the solar magnesium abundance log ?⊙ (Mg) = 7.55 ± 0.02 , as well as with the proto-Sun abundance log ? ps (Mg) = 7.62 ± 0.02 . Thus, it is confirmed that the Sun and the B-type MS stars in our neighbourhood have the same metallicity. |
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| Keywords: | stars: abundances stars: atmospheres stars: early-type |
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