发表机构
University of California, Berkeley; The Ohio State University; Center for Cosmology and Astroparticle Physics, The Ohio State University; California Institute of Technology; Leibniz-Institut for Astrophysics Potsdam (AIP); Tufts University（加州大学伯克利分校; 俄亥俄州立大学; 俄亥俄州立大学宇宙学与天体粒子物理中心; 加州理工学院; 波茨坦莱布尼茨天体物理研究所; 塔夫茨大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究利用TESS测光和多种光谱仪，对15个贫金属分离食双星进行精确质量和半径测量，发现最贫金属系统J0001+2156，并更新了主序恒星质量-半径经验关系。
AI 中文摘要
分离食双星长期以来一直作为与恒星模型进行直接比较的基本基准。通过结合分离食双星的光变曲线和视向速度轨道，可以精确测量两个子星的质量和半径。然而，食双星目录主要由太阳金属丰度恒星主导。在此，我们利用TESS测光、Gaia XP光谱、大型光谱巡天和银河系运动学，表征了十五个选择为$[\rm{M/H}]\lesssim -0.5$的食双星系统。我们使用了三台光谱仪：大双筒望远镜上的PEPSI、自动行星搜寻望远镜上的Levy光谱仪以及SMARTS 1.5米望远镜上的CHIRON。我们联合建模光变曲线和视向速度，测量恒星质量和半径，中值分数不确定度小于1%。我们使用光谱分离技术提取两颗恒星的光谱，并使用光谱合成代码Korg进行建模。我们发现三个系统的$[\rm{M/H}] < -2.0$，其中两个在运动学上与银河系晕一致。J0001+2156的$[\rm{M/H}]=-2.51$，使其成为迄今表征的最贫金属分离食双星。其余十二个系统中的十一个具有$[\rm{M/H}] \lesssim -0.5$，并分为高度（$[\alpha/\rm{M}] > 0.25$）和中度（$[\alpha/\rm{M}] < 0.25$）α增强。我们将测量的质量和半径与理论等时线预测进行比较，并估计双星的年龄。我们估计的年龄典型不确定度$\lesssim 0.5$ Gyr，其中三个双星的估计年龄大于10 Gyr，最高达$13.8^{+0.8}_{-0.7}$ Gyr。最后，我们使用621颗恒星的样本更新了主序上恒星质量和半径的经验关系。
英文摘要
Detached eclipsing binaries have long served as fundamental benchmarks for making direct comparisons with stellar models. By combining the light curve and radial velocity orbit of a detached eclipsing binary, precise masses and radii can be measured for both components. However, catalogs of eclipsing binaries are dominated by solar-metallicity stars. Here we characterize fifteen eclipsing binaries selected to have $[\rm{M/H}]\lesssim -0.5$ using TESS photometry, Gaia XP spectra, large spectroscopic surveys, and Galactic kinematics. We use three spectrographs, PEPSI on the Large Binocular Telescope, the Levy spectrograph on the Automated Planet Finder telescope, and CHIRON on the SMARTS 1.5m telescope. We jointly model the light curves and radial velocities and measure the stellar masses and radii with median fractional uncertainties of < 1%. We use spectral disentangling to extract the spectra of both stars and model them using the spectral synthesis code Korg. We find three systems with $[\rm{M/H}] < -2.0$, two of which are kinematically consistent with the Milky Way's halo. J0001+2156 has $[\rm{M/H}]=-2.51$, making it the most metal-poor detached eclipsing binary characterized to date. Eleven of the twelve other systems have $[\rm{M/H}] \lesssim -0.5$ and are split between being highly ($[α/\rm{M}] > 0.25$) and moderately ($[α/\rm{M}] < 0.25$) $α$-enhanced. We compare our measured masses and radii to predictions from theoretical isochrones and estimate the ages of the binaries. We estimate ages with typical uncertainties of $\lesssim 0.5$ Gyr, and three of the binaries have estimated ages greater than 10 Gyr, up to $13.8^{+0.8}_{-0.7}$ Gyr. Finally, we update the empirical relations for stellar masses and radii on the main sequence using a sample of 621 stars.
CommentsSubmitted to PASP. 37 pages, 20 figures
