AI 中文总结
研究对G型双星CW Cas进行多波段研究，结合光谱和光度数据确定其参数，发现光变曲线不对称及暗斑活动周期变化，通过轨道周期分析发现第三体，推测其为致密天体，还发现目视伴星，表明其是层级四重系统，为相关研究提供了有价值的实验室。
AI 中文摘要
我们对参数尚未完全确定的G型双星CW Cas进行了全面的多波段光度和光谱研究。通过双线光谱径向速度曲线得到可靠的质量比q = 1.88(9)。结合多波段数据发现CW Cas是W型浅相接双星，填充因子为15%，两子星质量分别为0.98(6)M⊙和0.52(4)M⊙，间距2.25(5)R⊙。光变曲线极大值存在不对称性，由至少一个子星表面的暗斑解释，不同年份光变曲线显示暗斑活动有周期约1250天的循环变化。通过O - C图分析125年的轨道周期，发现有第三体导致的长期减小和周期性振荡，第三体轨道周期P3 = 99.4(6)年，最小质量M3 = 0.91(1)M⊙，且在光谱和光度数据中未检测到其特征，推测为致密天体。基于盖亚DR3天体测量数据还发现了一个目视伴星，表明CW Cas是层级四重系统的一部分，它为探测包含致密天体的2 + 1 + 1层级多重系统提供了有价值的实验室。
英文摘要
We present a comprehensive multiband photometric and spectroscopic study of the G-type binary CW Cas whose parameters have not been well determined. Our double-lined spectroscopic radial velocity curve of this system yields a reliable mass ratio of $q = 1.88(9)$. By combining $BVR_{c}I_{c}$ bands, TESS light curves and radial velocity curves, we found that CW Cas is a W-subtype shallow contact binary with a fill-out factor of 15\%. The components have masses of $0.98(6)M_{\odot}$ and $0.52(4)M_{\odot}$, separated by $2.25(5)R_{\odot}$. A notable asymmetry in the maxima of the light curves was detected and explained by a dark spot located on the surface of at least one component. Comparison of light curves from different years revealed that these dark spot activities exhibit cyclic variations with an approximate period of 1250 days. Orbital period analysis via O-C diagram spanning 125 years shows a long-term decrease superimposed with periodic oscillation caused by the light-travel-time effect (LTTE) due to a third body. This tertiary component has an orbital period of $P_{3} = 99.4(6)$ years and a minimal mass of $M_{3}=0.91(1)M_{\odot}$. The absence of detectable signatures for this massive object in either spectroscopic or photometric datasets implies it must be a compact object such as a white dwarf or neutron star. Furthermore, a visual companion was identified based on Gaia DR3 astrometric data, suggesting that CW Cas is part of a hierarchical quadruple system. As such, CW Cas represents a valuable laboratory for probing 2+1+1 hierarchical multiple system hosting compact object.
CommentsThis paper have 16 pages, 8 figures and 8 tables. This paper presents an investigation of an unseen third body in the hierarchical triple system of the eclipsing close binary star CW Cas
