The Araucaria Project: High-precision orbital parallax and masses of the eclipsing binary TZ~Fornacis
The Araucaria Project: High-precision orbital parallax and masses of the eclipsing binary TZ~Fornacis
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南洋杉计划：食双星 TZ~Fornacis 的高精度轨道视差和质量
DOI：
10.1051/0004-6361/201526764
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发表时间：
2015
期刊：
影响因子：
--
通讯作者：
S. Villanova
中科院分区：
文献类型：
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作者：
A. Gallenne;G. Pietrzyński;D. Graczyk;P. Konorski;P. Kervella;A. Mérand;W. Gieren;R. Anderson;S. Villanova
背景：独立距离估计对于检查其他距离指标的精度特别有用，而准确且精确的质量对于约束进化模型是必要的。目的：目标是使用完全几何和经验的方法以低于 1\,\% 的精度测量分离的食双星 TZ~For 的质量和距离。方法：我们使用 VLTI/PIONIER 组合器获得了 TZ~For 的首次干涉观测，并将其与新的精确径向速度测量相结合，得出其三维轨道、质量和距离。结果：PIONIER 在每个观测历元都很好地解析了该系统，这允许与 11 个天体测量位置进行组合拟合。我们得出的值与之前的工作非常吻合，但精度有所提高。我们测量两个组件的质量为 $M_1 = 2.057 \pm 0.001\,M_\odot$ 和 $M_2 = 1.958 \pm 0.001\,M_\odot$。与恒星演化模型的比较得出该系统的年龄为 $1.20 \pm 0.10$\,Gyr。我们还导出了到系统的距离，精度为 1.1\,\%：$d = 185.9 \pm 1.9$\,pc。与食双星的如此精确的几何距离为测试晚型恒星表面亮度-颜色关系的绝对校准提供了独特的机会，并且还将提供检查未来盖亚测量可能存在的系统误差的最佳机会。
Context: Independent distance estimates are particularly useful to check the precision of other distance indicators, while accurate and precise masses are necessary to constrain evolution models. Aim: The goal is to measure the masses and distance of the detached eclipsing-binary TZ~For with a precision level lower than 1\,\% using a fully geometrical and empirical method. Method: We obtained the first interferometric observations of TZ~For with the VLTI/PIONIER combiner, which we combined with new and precise radial velocity measurements to derive its three-dimensional orbit, masses, and distance. Results: The system is well resolved by PIONIER at each observing epoch, which allowed a combined fit with eleven astrometric positions. Our derived values are in a good agreement with previous work, but with an improved precision. We measured the mass of both components to be $M_1 = 2.057 \pm 0.001\,M_\odot$ and $M_2 = 1.958 \pm 0.001\,M_\odot$. The comparison with stellar evolution models gives an age of the system of $1.20 \pm 0.10$\,Gyr. We also derived the distance to the system with a precision level of 1.1\,\%: $d = 185.9 \pm 1.9$\,pc. Such precise and accurate geometrical distances to eclipsing binaries provide a unique opportunity to test the absolute calibration of the surface brightness-colour relation for late-type stars, and will also provide the best opportunity to check on the future Gaia measurements for possible systematic errors.