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arXiv 2404.15411astro-ph.SR
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基于LAMOST光谱的约11,000颗天琴座RR型星的恒星大气参数

Stellar atmospheric parameters of $\sim$ 11,000 RR Lyrae stars from LAMOST Spectra

Jiangtao Wang, Jianrong Shi, Jianning Fu, Weikai Zong, Chunqian Li

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17 pages, 10 figures, accepted for publication in ApJs
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AI总结：

本文提出改进的模板匹配方法，基于LAMOST单历元光谱测定了约1.1万颗天琴座RR型星的径向速度和恒星大气参数，并总结了其在脉动相期间的变化特征。

摘要：

准确测定天琴座RR型星（RRLs）的恒星大气参数需要较短的单次光谱曝光以减轻脉动效应。我们提出了改进的模板匹配方法，利用LAMOST（大天区面积多目标光纤光谱天文望远镜，也称为郭守敬望远镜）的单历元光谱来测定RRLs的恒星大气参数。我们分别从LAMOST的42,729条低分辨率光谱（LRS）和7,064条中分辨率光谱（MRS）中，测定了10,486颗和1,027颗RRLs的径向速度和恒星大气参数（有效温度：$T_\mathrm{eff}$，表面重力：$\log{g}$，以及金属丰度：[M/H]）。我们的结果与其他数据库的参数吻合良好，其中LRS/MRS的$T_\mathrm{eff}$、$\log{g}$和[M/H]的外部不确定度分别估计为314/274 K、0.42/0.29 dex和0.39/0.31 dex。最后，我们总结了RRLs在脉动相期间径向速度（$RV$）和恒星大气参数的变化特征。对于RRab，来自H$α$线（$RV_\mathrm{Hα}$）和金属线（$RV_\mathrm{metal}$）的$RV$峰峰值振幅（$A_\mathrm{ptp}$）之间存在$28\pm21$ km/s的显著差异，而对于RRc，该差异仅为$4\pm17$ km/s。RRab和RRc的$T_\mathrm{eff}$的$A_\mathrm{ptp}$分别为$930\pm456$ K和$409\pm375$ K。RRab的$\log{g}$在$φ= 0.9$相位附近表现出约$0.23\pm0.42$ dex的轻微变化，而RRc的$\log{g}$几乎保持恒定。RRab和RRc的[M/H]在$φ= 0.9$相位附近分别表现出约$0.25\pm0.50$ dex和$0.28\pm0.55$ dex的微小变化。

英文摘要：

Accurate determination of the stellar atmospheric parameters of RR Lyrae stars (RRLs) requires short individual exposures of the spectra to mitigate pulsation effects. We present improved template matching methods to determine the stellar atmospheric parameters of RRLs from single-epoch spectra of LAMOST (Large Sky Area Multi-Object Fiber Spectroscopic Telescope, also known as the Guoshoujing telescope). We determine the radial velocities and stellar atmospheric parameters (effective temperature: $T_\mathrm{eff}$, surface gravity: $\log{g}$, and metallicity: [M/H]) of 10,486 and 1,027 RRLs from 42,729 low-resolution spectra (LRS) and 7,064 medium-resolution spectra (MRS) of LAMOST, respectively. Our results are in good agreement with the parameters of other databases, where the external uncertainties of $T_\mathrm{eff}$, $\log{g}$, and [M/H] for LRS/MRS are estimated to be 314/274 K, 0.42/0.29 dex, and 0.39/0.31 dex, respectively. We conclude with the variation characteristics of the radial velocities ($RV$) and stellar atmospheric parameters for RRLs during the pulsation phase. There is a significant difference of $28\pm21$ km/s between the peak-to-peak amplitude ($A_\mathrm{ptp}$) of $RV$ from H$α$ line ($RV_\mathrm{Hα}$) and from metal lines ($RV_\mathrm{metal}$) for RRab, whereas it is only $4\pm17$ km/s for RRc. The $A_\mathrm{ptp}$ of $T_\mathrm{eff}$ is $930\pm456$ and $409\pm375$ K for RRab and RRc, respectively. The $\log{g}$ of RRab show mild variation of approximately $0.23\pm0.42$ dex near the phase of $φ= 0.9$, while that of RRc almost remains constant. The [M/H] of RRab and RRc show a minor variation of about $0.25\pm0.50$ and $0.28\pm0.55$ dex, respectively, near the phase of $φ= 0.9$.

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