近相接双星中质量转移的测光效应与统计特征研究

The mass-transfer process in close binary has been one of the hotspots in astrophysics, and its research has an important theoretical significance for understanding the evolution of close binaries. In recent years, it has been gradually recognized that near-contact binary can be used as an ideal object for studying the mass-transfer process due to its unique geometric structure and physical properties. In particular, the photometric effects (asymmetry, distortion, or local humps of light curves) caused by mass transfer provide a new way for us to study the mass-transfer process. At present, this scheme has received little attention, especially, the statistical characteristics of photometric effects caused by mass transfer and statistical relations between mass transfer and its photometric effects still lack a systematic research, and so that the physical image and theoretical mechanism of mass transfer is still unclear. In this project, we will focus on the observations and photometry of near-contact binaries, mainly study the statistical correlation between mass transfer and its photometric effects. By combining the orbital period changes with photometric effects caused by mass transfer, the physical mechanism that mass transfer generates starspots will be investigated, and the role of mass transfer in the evolution of near-contact binaries will be explored. The research of this project will be helpful for us to identify the different origins of asymmetric light curves, quantify the mass-transfer rate and reveal the evolutionary connects between near-contact binaries and other types of close binaries.

密近双星中的质量转移过程一直是天体物理研究领域的热点之一，其研究对于理解密近双星的演化具有重要的理论意义。近年来，人们已经逐渐认识到近相接双星因其独特的几何结构和物理性质可作为研究质量转移的理想对象，特别是其中的质量转移所产生的测光效应（光变曲线的非对称、畸变或局部驼峰等）为我们研究质量转移过程提供了一种新的途径。目前，这一方案仍关注较少，尤其是质量转移产生的测光效应的统计特征及其与质量转移的统计关系等尚缺乏系统的研究，其物理图像与理论机制尚不清晰。本项目将以近相接双星为对象，开展近相接双星的观测与测光研究；通过结合质量转移所致的轨道周期变化与测光效应，着重研究质量转移与测光效应的统计相关性和质量转移形成黑子的物理机制，探索质量转移在近相接双星演化中的作用。本项目的研究将有助于人们有效甄别非对称光变曲线的不同起源、明确质量转移率和揭示近相接双星与其他密近双星的演化联系。

近相接双星是其两子星在结构上接近相接或浅度相接的一类特殊密近双星，它们处于双星演化链的特殊演化阶段，是联系分离双星和相接双星的桥梁。在近相接双星中，质量转移是一个非常普遍的物理过程，它对于密近双星的演化状态和演化归宿有着重要的影响，是当前密近双星研究领域的一个热点。理论上，密近双星中的质量转移可在受主子星表面产生冲击黑子，导致其光变曲线出现诸如非对称性、畸变或局部驼峰等显著的可观测效应。而近相接双星，因其特殊的几何结构与物理性质，是研究物质转移过程的良好载体。本项目开展了一批近相接双星的测光、光谱和轨道周期变化研究，并利用约束三体理论和单粒子轨道模拟，发展了质量转移形成冲击黑子的理论模型，在几颗近相接双星中进行了应用，很好地解释了观测到的光变曲线非对称性的可观测效应。其次，基于质量转移和经典的洛希势模型，从理论上推导了两子星临界洛希半径与质量比之间的理论关系，同时结合热弛豫震荡理论，为探讨近相接双星的演化状态和与半分离/过相接双星的演化联系提供了一种参考方案。最后，我们结合测光解和Gaia的距离，发展了一种确定食双星绝对物理参数的标准程序，并利用其计算了几颗密近双星的物理参数。本项目所发展的质量转移形成冲击黑子的理论模型、推导的洛希半径与质量比的理论关系和确定绝对物理参数的计算方案，对于甄别光变曲线非对称性的物理起源、理解近相接双星与半分离和过相接双星的演化联系以及和探索密近双星的统计性质和演化链具有一定的理论价值。本项目顺利完成了预定的研究目标，累计发表标注致谢的SCI论文8篇，已接收待发表论文1篇，培养毕业的硕士研究生4名。