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arXiv 1709.01689astro-ph.SR
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可能的三体系统中盾牌座$δ$星AN Lyncis的脉动和周期变化

Pulsations and Period Variations of the $δ$ Scuti Star AN Lyncis in a possible three-body system

Gang Li, Jianning Fu, Jie Su, Lester Fox-Machado, Raul Michel, Zhen Guo, Jinzhong Liu, Guojie Feng

备注：
14 pages, 8 tables, 17 figures, accepted by mnras
发表信息：
2018MNRAS.473..398L
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摘要：

2008年至2016年间，中国国家天文台兴隆站的85厘米望远镜，墨西哥SPM天文台的84厘米望远镜和中国新疆天文台的南山一米宽视场望远镜对$δ$ Scuti星AN Lyn进行了观测。总共获得了$V$中50个夜晚和$R$中34个夜晚的数据。利用2014年兴隆站和SPM观测站的双站观测资料，利用傅里叶分解方法对脉动频率进行了分析。解决了两个独立的频率，包括一个非径向模式。用MESA程序建立了一系列恒星模型轨道，通过对恒星质量、金属丰度、年龄和周期变化率的拟合，得到了$M = 1.70 \pm 0.05~\mathrm{M_{\odot}}$、$Z = 0.020 \pm 0.001$、$1.33 \pm 0.01$和周期变化率$1/P\cdot \mathrm{d}P/\mathrm{d}t =1.06 \times 10^{-9} ~\mathrm{yr^{-1}} $的最佳拟合模型，将恒星定位在演化阶段接近终龄主序（TAMS）的位置。O-C图提供了$1/P \cdot \mathrm{d}P /\mathrm{d}t =4.5(8)\times10^{-7}~\mathrm{yr^{-1}}$的周期变化率。然而，由模型计算的周期变化率比由O-C图导出的周期变化率小两个数量级。与正弦函数签名一起，周期变化被认为是由具有两个低光度分量的三体系统的轨道运动的光旅行时间效应主导的，而不是恒星演化效应。

英文摘要：

Observations for the $δ$ Scuti star AN Lyn have been made between 2008 and 2016 with the 85-cm telescope at Xinglong station of National Astronomical Observatories of China, the 84-cm telescope at SPM Observatory of Mexico and the Nanshan One meter Wide field Telescope of Xinjiang Observatory of China. Data in $V$ in 50 nights and in $R$ in 34 nights are obtained in total. The bi-site observations from both Xinglong Station and SPM Observatory in 2014 are analyzed with Fourier Decomposition to detect pulsation frequencies. Two independent frequencies are resolved, including one non-radial mode. A number of stellar model tracks are constructed with the MESA code and the fit of frequencies leads to the best-fit model with the stellar mass of $M = 1.70 \pm 0.05~\mathrm{M_{\odot}}$ , the metallicity abundance of $Z = 0.020 \pm 0.001$, the age of $1.33 \pm 0.01$ billion years and the period change rate $1/P\cdot \mathrm{d}P/\mathrm{d}t =1.06 \times 10^{-9} ~\mathrm{yr^{-1}} $, locating the star at the evolutionary stage close to the terminal age main sequence (TAMS). The O-C diagram provides the period change rate of $1/P \cdot \mathrm{d}P /\mathrm{d}t =4.5(8)\times10^{-7}~\mathrm{yr^{-1}}$. However, the period change rate calculated from the models is smaller in two orders than the one derived from the O-C diagram. Together with the sinusoidal function signature, the period variations are regarded to be dominated by the light-travel time effect of the orbital motion of a three-body system with two low-luminosity components, rather than the stellar evolutionary effect.

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