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arXiv · 2005.11027

Neon Abundances of B-stars in the Solar Neighborhood

Sofya Alexeeva·Tianxiang Chen·Tatyana Ryabchikova·Weibin Shi·Kozo Sadakane·Masayoshi Nishimura·Gang Zhao
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Abstract

We constructed a comprehensive model atom for NeI -- NeII using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for NeI and NeII in classical 1D models representing the atmospheres of B-type stars. We find that the large NLTE strengthening of the NeI lines corresponding to the 2p$^5$3p $-$ 2p$^5$3s transitions array occurs due to extremely small photoionization cross-sections of 2p$^5$3s levels that leads to strong overpopulation of these levels relative to their LTE populations. The deviations from LTE for the most NeII lines are small and do not exceed 0.11~dex in the absolute value. We analysed 20 lines of NeI and 13 lines of NeII for twenty-four B-type stars in the temperature range of 10\,400 $\le$ \Teff\ $\le$ 33\,400~K. For five stars, the NLTE leads to consistent abundances of NeI and NeII, while the difference in LTE abundance can reach up to 0.50~dex. The using of the experimental oscillator strengths recently measured by Piracha et al. (2015) leads to smaller line-by-line scatter for the most investigated stars. The averaged neon abundance in twenty-four B-type stars in solar neighborhood is 8.02$\pm$0.05. This value may provide indirect constraints on solar photospheric neon abundance.

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Sofya Alexeeva, Tianxiang Chen, Tatyana Ryabchikova, Weibin Shi, Kozo Sadakane, Masayoshi Nishimura, Gang Zhao. 2020-05-22. Neon Abundances of B-stars in the Solar Neighborhood. https://doi.org/10.3847/1538-4357%2Fab9306

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