论文标题
WOC 4540：非常长的轨道周期蓝色Straggler的详细分析
WOCS 4540: Detailed Analysis of a Very Long Orbital Period Blue Straggler
论文作者
论文摘要
WOCS 4540是最长的轨道周期（$ p _ {\ rm orb} = 3030 $ days）蓝色straggler（BSS） - 旧开放群集NGC 188中的白色矮人（WD）对。它还包含集群中最发光的BS之一。先前的\ textit {Hubble Space望远镜} COS光谱法测量的WD质量为0.53 $ M _ {\ odot} $，指示碳氧气WD，并提出先前从渐近分支巨头（AGB）的质量转移。系统演化的详细建模，包括红色巨型分支相风传递，AGB Wind Roche-Lobe溢出和常规的Roche-Lobe Overflow，是通过用于实验的恒星天体物理学实验的模块进行的。最佳拟合模型与BSS，WD和二进制系统的广泛观察性约束产生了极好的一致性。为了产生观察到的BSS的亮度和有效温度，所有三个供体质量转移机制都对构建1.5 $ M _ {\ odot} $ BSS的贡献类似。总体质量转移效率为55％。常规的Roche-Lobe溢出仅发生在最大的AGB热脉冲期间，但在75％的效率下产生的积聚率很高，并且短暂（小于1 Myr）从增生器中提高了很高的发光度。
WOCS 4540 is the longest orbital period ($P_{\rm orb}=3030$ days) blue straggler (BSS) - white dwarf (WD) pair in the old open cluster NGC 188 . It also contains one of the most luminous BSS in the cluster. Prior \textit{Hubble Space Telescope} COS spectroscopy measured a WD mass of 0.53 $M_{\odot}$, indicative of a carbon-oxygen WD and suggesting previous mass transfer from an asymptotic branch giant (AGB). Detailed modeling of the system evolution, including red giant branch phase wind mass transfer, AGB wind Roche-lobe overflow and regular Roche-lobe overflow, is done with Modules for Experiments in Stellar Astrophysics. The best-fit model produces excellent agreement with a wide array of observational constraints on the BSS, the WD and the binary system. To produce the observed luminosity and effective temperature of the BSS, all three donor mass-transfer mechanisms contribute similarly to build a 1.5 $M_{\odot}$ BSS. The overall mass-transfer efficiency is 55%. Regular Roche-lobe overflow occurs only during the largest AGB thermal pulse, but yields a very high accretion rate at 75% efficiency and briefly (less than 1 Myr) a very high luminosity boost from the accretor.
