晚B型食双星系统御夫座AR A和B的光谱研究：旨在厘清大气参数与化学丰度的差异
Spectroscopic study of the late B-type eclipsing binary system AR Aurigae A and B: Towards clarifying the differences in atmospheric parameters and chemical abundances
AI总结：
本研究针对晚B型食双星御夫座AR A+B开展光谱分析，测定了两颗子星的大气参数与28种元素丰度，发现二者化学丰度分布存在显著差异，为理解恒星化学异常的形成临界条件提供了关键观测依据。
摘要：
御夫座AR A+B是具有天体物理研究价值的密近双星，因为据报道，两颗相似的晚B型矮星之间存在不同的表面组成。本研究基于解缠光谱对该系统开展了新的光谱研究，以测定其大气参数和元素丰度。通过Fe II线的等值宽度测定，A星和B星的有效温度与微湍流速度分别为(11150K, 0.9km/s)和(10650K, 0.1km/s)。研究推导了28种元素的化学丰度，同时对原子序数Z≤15的元素考虑了非局部热动平衡（non-LTE）效应。研究阐明了[X/H]（元素X相对于太阳的丰度）的以下趋势：(1) 定性来看，[X/H]整体呈现随Z增大而升高的粗略趋势，且A星的梯度比B星更陡。(2) 但A星的丰度存在相当大的离散性，因为在特定元素中观测到了显著的异常特征，反映了HgMn星的特性（例如N、Al、Sc、Ni极度匮乏；P、Mn显著超丰）。(3) 相比之下，B星的[X/H]随Z的变化趋势近乎线性，离散度很小。这些观测事实可能成为理解化学异常出现临界条件的关键。
英文摘要：
AR Aur A+B is a close binary of astrophysical interest, because dissimilar surface compositions are reported between similar late B-type dwarfs. A new spectroscopic study on this system was carried out based on the disentangled spectra, in order to determine their atmospheric parameters and elemental abundances, The effective temperature and microturbulence (determined from the equivalent widths of Fe II lines) turned out (11150K, 0.9km/s) and (10650K, 0.1km/s) for A and B. The chemical abundances of 28 elements were derived while taking into account the non-LTE effect for Z<=15 elements (Z: atomic number). The following trends were elucidated for [X/H] (abundance of X relative to the Sun): (1) Qualitatively, [X/H] shows a rough global tendency of increasing with Z, with the gradient steeper for A than for B. (2) However, considerable dispersion is involved for A, since prominently large peculiarities are seen in specific elements reflecting the characteristics of HgMn stars (e.g., very deficient N, Al, Sc, Ni; markedly overabundant P, Mn). (3) In contrast, the Z-dependence of [X/H] for B tends to be nearly linear with only a small dispersion. These observational facts may serve as a key to understanding the critical condition for the emergence of chemical anomaly.
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