论文标题
B型超级巨人的定量光谱
Quantitative spectroscopy of B-type supergiants
论文作者
论文摘要
语境。 B型Supergiants是解决各种天体物理主题的多功能工具，从恒星和银河发展的恒星大气到宇宙距离量表。目标。 A hybrid non-LTE approach - line-blanketed model atmospheres computed under the assumption of local thermodynamic equilibrium (LTE) in combination with line formation calculations that account for deviations from LTE - is tested for quantitative analyses of B-type supergiants with masses $M<30 M_{\odot}$, characterising a sample of 14 Galactic objects.方法。用库鲁兹的ATLAS12代码与非LTE线形成代码的细节/表面相比，用Kurucz的ATLAS12代码计算的静水平面平行大气结构和合成光谱与具有TLUSTY的全非LTE计算结果进行了比较，并研究了模型对模型的影响。使用鲜明的氢系和多个金属电离平衡和元素丰度分析了高分辨率光谱的大气参数。基本恒星参数是通过考虑恒星进化轨迹和GAIA EDR3可视性来得出的。星际对目标恒星的红色红色是通过将模型光谱能量分布与观察到的恒星匹配确定的。结果。我们的混合非LTE方法事实证明，考虑到B型超级巨头的较深光时层的静液压全非LTE建模。湍流压力可能与大于10 km s $^{ - 1} $的微涡轮速度相关。通过同时使多个指标达成共识，可以实现所有派生参数的高精度和准确性。化学物种的丰度（HE，C，N，O，NE，MG，AL，SI，S，AR，FE）的不确定性为0.05至0.10 dex。派生的比率N/C与N/O紧密地遵循日内瓦恒星进化模型的预测。
Context. B-type supergiants are versatile tools to address various astrophysical topics, ranging from stellar atmospheres over stellar and galactic evolution to the cosmic distance scale. Aims. A hybrid non-LTE approach - line-blanketed model atmospheres computed under the assumption of local thermodynamic equilibrium (LTE) in combination with line formation calculations that account for deviations from LTE - is tested for quantitative analyses of B-type supergiants with masses $M<30 M_{\odot}$, characterising a sample of 14 Galactic objects. Methods. Hydrostatic plane-parallel atmospheric structures and synthetic spectra computed with Kurucz's Atlas12 code together with the non-LTE line-formation codes Detail/Surface are compared to results from full non-LTE calculations with Tlusty, and the effects of turbulent pressure on the models are investigated. High-resolution spectra are analysed for atmospheric parameters, using Stark-broadened hydrogen lines and multiple metal ionisation equilibria, and for elemental abundances. Fundamental stellar parameters are derived by considering stellar evolution tracks and Gaia EDR3 parallaxes. Interstellar reddening towards the target stars is determined by matching model spectral energy distributions to observed ones. Results. Our hybrid non-LTE approach turns out to be equivalent to hydrostatic full non-LTE modelling for the deeper photospheric layers of the B-type supergiants considered. Turbulent pressure can become relevant for microturbulent velocities larger than 10 km s$^{-1}$. High precision and accuracy is achieved for all derived parameters by bringing multiple indicators to agreement simultaneously. Abundances for chemical species (He, C, N, O, Ne, Mg, Al, Si, S, Ar, Fe) are derived with uncertainties of 0.05 to 0.10 dex. The derived ratios N/C vs. N/O tightly follow the predictions from Geneva stellar evolution models.
