论文标题
进化的黯然失色的二进制文件和开放群集NGC 752的年龄
Evolved Eclipsing Binaries and the Age of the Open Cluster NGC 752
论文作者
论文摘要
我们介绍了在开放群集NGC 752的转盘上进行两次分离的黯然失色的二进制二进制的分析：1.01天二进制DS和15.53 d bd $+$ 37 410。 = 2.185 \ pm0.004 \ pm0.008 r_ \ odot $，$ m_2 = 1.184 \ pm0.001 \ pm0.003 m_ \ odot $，$ r_2 = 1.200 \ pm0.003 \ pm0.003 \ pm0.005 r_ \ odot $。我们要么确认或新识别二元恒星在二元中的异常特征：发现主要恒星比主序列关闭略高，而且与模型相比，其发光度的亮度差异更大（模型的亮度太大，大约40％），而次要恒星与同一颗粒中的其他主序列相比，次级恒星的尺寸过大，并且较酷。证据表明，这两个恒星都非标准进化，但是大多数合理的路径无法解释主要恒星的低光度。 BD $+$ 37 410每个周期只有一个日食，但是广泛的光谱观测和苔丝光曲线很好地限制了恒星质量：$ m_1 = 1.717 \ pm0.011 m_ \ odot $和$ m_2 = 1.175 \ pm0.005 m_ \ odot $。主序列主要星的半径接近$ 2.9R_ \ odot $确定地需要大量的对流核心过圈（$> 0.2 $压力尺度的高度），其质量的型号和多行证据指向$ 1.61 \ pm0.03 \ pm0.03 \ pm0.03 \ pm0.05 $ gyr（统计和系统的不确定性）。由于NGC 752目前正在从非脱位到退化的过渡，因此他点燃其红色团星，BD $+$ 37 410 A直接限制了发生这种过渡的恒星质量。
We present analyses of improved photometric and spectroscopic observations for two detached eclipsing binaries at the turnoff of the open cluster NGC 752: the 1.01 day binary DS And and the 15.53 d BD $+$37 410. For DS And, we find $M_1 = 1.692\pm0.004\pm0.010 M_\odot$, $R_1 = 2.185\pm0.004\pm0.008 R_\odot$, $M_2 = 1.184\pm0.001\pm0.003 M_\odot$, and $R_2 = 1.200\pm0.003\pm0.005 R_\odot$. We either confirm or newly identify unusual characteristics of both stars in the binary: the primary star is found to be slightly hotter than the main sequence turn off and there is a more substantial discrepancy in its luminosity compared to models (model luminosities are too large by about 40%), while the secondary star is oversized and cooler compared to other main sequence stars in the same cluster. The evidence points to non-standard evolution for both stars, but most plausible paths cannot explain the low luminosity of the primary star. BD $+$37 410 only has one eclipse per cycle, but extensive spectroscopic observations and the TESS light curve constrain the stellar masses well: $M_1 = 1.717\pm0.011 M_\odot$ and $M_2 = 1.175\pm0.005 M_\odot$. The radius of the main sequence primary star near $2.9R_\odot$ definitively requires large convective core overshooting ($> 0.2$ pressure scale heights) in models for its mass, and multiple lines of evidence point toward an age of $1.61\pm0.03\pm0.05$ Gyr (statistical and systematic uncertainties). Because NGC 752 is currently undergoing the transition from non-degenerate to degenerate He ignition of its red clump stars, BD $+$37 410 A directly constrains the star mass where this transition occurs.
