论文标题
重新讨论黯然失色的二进制文件。纸XI。 ZZ Ursae Majoris，一种太阳能系统，显示了整体蚀和半径差异
Rediscussion of eclipsing binaries. Paper XI. ZZ Ursae Majoris, a solar-type system showing total eclipses and a radius discrepancy
论文作者
论文摘要
ZZ UMA是一种轨道周期为2.299 d的脱落的二进制，显示了总叶绿和星形活性。我们使用了从过渡系外行星调查卫星（TESS）和两组发表的径向速度组中的光曲线的五个扇区，以建立系统的性质至高精度。主恒星的质量为1.135 +/- 0.009 msun，半径为1.437 +/- 0.007 rsun，而二级组件的质量为0.965 +/- 0.005 msun，半径为1.075 +/- 0.005 rsun。主要恒星的特性与略微超值金属性和5.5 GYR的理论预测一致。次级恒星的特性不同意这些和所有其他模型预测：虽然光度与模型非常吻合，但半径太大，温度太低。这些是半径差异的定义特征，已有40年了，但仍然是一个积极的研究领域。星形活性在光曲线的放下外部部分，在日食深度的系统变化中以及在系统的中分辨率频谱中的CA H和K线的发射中很明显。在苔丝观察过程中，恒星之间的光和表面亮度比分别线性变化20％和14％，但几何参数却没有。对现场活动的对象的研究应通过在可能的长时间内使用观测值来解释这一点，并专注于完全分散的系统，其光曲线可以对系统的物理性质进行更强大的测量。
ZZ UMa is a detached eclipsing binary with an orbital period of 2.299 d that shows total eclipses and starspot activity. We used five sectors of light curves from the Transiting Exoplanet Survey Satellite (TESS) and two published sets of radial velocities to establish the properties of the system to high precision. The primary star has a mass of 1.135 +/- 0.009 Msun and a radius of 1.437 +/- 0.007 Rsun, whilst the secondary component has a mass of 0.965 +/- 0.005 Msun and a radius of 1.075 +/- 0.005 Rsun. The properties of the primary star agree with theoretical predictions for a slightly super-solar metallicity and an age of 5.5 Gyr. The properties of the secondary star disagree with these and all other model predictions: whilst the luminosity is in good agreement with models the radius is too large and the temperature is too low. These are the defining characteristics of the radius discrepancy which has been known for 40 years but remains an active area of research. Starspot activity is evident in the out-of-eclipse portions of the light curve, in systematic changes in the eclipse depths, and in emission at the Ca H and K lines in a medium-resolution spectrum of the system. Over the course of the TESS observations the light and surface brightness ratios between the stars change linearly by 20% and 14%, respectively, but the geometric parameters do not. Studies of objects showing spot activity should account for this by using observations over long time periods where possible, and by concentrating on totally-eclipsing systems whose light curves allow more robust measurements of the physical properties of the system.
