标题： 食双星的相对演化：测量球状星团年龄和氦丰度的工具 显示英文标题

标题： Relative evolution of eclipsing binaries: A tool to measure globular cluster ages and He abundances

摘要： 球状星团（GCs）是宇宙中最古老的天体之一，其年龄可以直接测量，因此在宇宙学中起着重要作用。 另一方面，这个年龄对氦丰度非常敏感，而通过光谱学无法可靠地测量球状星团恒星的氦丰度。 靠近转折点（TO）的分离食双星（DEBs）在这方面可能起到重要作用。 本研究的目的是探讨一种可能性：通过处理构成TO双星系统的恒星的差分测量，并假设两颗恒星具有相同的年龄和氦丰度，可以比通过恒星的绝对参数获得更紧致、更稳健且依赖模型较少的后两个量的约束。 我们将V69（球状星团47 Tuc中的TO DEB对）中恒星的绝对参数和差分参数与两组不同的恒星演化轨迹进行比较，利用蒙特卡洛技术来估计其氦丰度和年龄，以及它们的不确定性。 我们发现，相对方法可以产生与文献中结果一致的年龄和氦丰度估计。 我们表明，我们的估计也更具模型独立性，对[Fe/H]的敏感性更低，并且比使用绝对方法获得的估计更具稳健性。 另一方面，相对分析在V69的情况下，统计不确定性大于其绝对对应项，因为这两颗恒星具有非常相似的特性。 对于其中一颗成分比另一颗演化的恒星对，统计不确定性可以降低。 我们的研究表明，本文提出的方法可能有助于稳健地约束球状星团的氦丰度和年龄。 显示英文摘要

摘要： Globular clusters (GCs) are among the oldest objects in the Universe for which an age can be directly measured, thus playing an important cosmological role. This age, on the other hand, depends sensitively on the He abundance, which cannot be reliably measured from spectroscopy in GC stars. Detached eclipsing binaries (DEBs) near the turnoff (TO) point may play an important role in this regard. The aim of this study is to explore the possibility that, by working with differential measurements of stars that comprise a TO binary system, and assuming both stars have the same age and He abundance, one can achieve tighter, more robust, and less model-dependent constraints on the latter two quantities than otherwise possible by working with the absolute parameters of the stars. We compare both absolute and differential parameters of the stars in V69, a TO DEB pair in the GC 47 Tuc, with two different sets of stellar evolutionary tracks, making use of a Monte Carlo technique to estimate its He abundance and age, along with their uncertainties. We find that the relative approach can produce age and He abundance estimates that are in good agreement with those from the literature. We show that our estimates are also less model-dependent, less sensitive to [Fe/H], and more robust to inherent model systematics than those obtained with an absolute approach. On the other hand, the relative analysis finds larger statistical uncertainties than does its absolute counterpart, at least in the case of V69, where both stars have very similar properties. For binary pairs in which one of the components is less evolved than the other, the statistical uncertainty can be reduced. Our study suggests that the method proposed in this work may be useful to robustly constrain the He abundance and ages of GCs.