不同光谱型相接双星O'Connell效应的统计研究

The O'Connell effect commonly appears on contact binaries. It is suggested that the O'Connell effect is closely related to magnetic activity of the component stars, circumstellar material around the binary system and mass transfer between the component stars. Based on the spectral data released by the LAMOST and the photometric data collected, the statistical result of the O'Connell effect on different spectral types' contact binaries will be built. Then, some important targets will be long time monitored. The observational data will be modeled with the Wilson–Devinney（W-D) program to obtain basic parameters of binary systems, such as mass ratio, orbital inclination, degree of contact. The effect of the basic parameters of binary systems on the O'Connell effect will be studied. The role that magnetic activity, circumstellar material and mass transfer have taken on the formation of the O'Connell effect will be analyzed. The relation and difference between early and late type contact binaries in their formation and evolution will be discussed.

相接双星中普遍存在O'Connell效应。研究表明，O'Connell效应的形成主要与三种因素有关：子星表面磁活动、双星系统周围的星周物质及两子星间的物质交流。本项目依托于我国重大科学工程LAMOST巡天所释放的双星光谱数据，结合项目组成员所在课题组数十年积累的双星测光数据积累，将对不同光谱型相接双星O'Connell效应的光变变幅予以统计，得到相接双星O'Connell效应的基本统计特性。然后，选取一批具有代表性的目标源，利用国内中小口径望远镜对其进行长期监测，利用测光解轨程序（Wilson–Devinney程序）对观测得到的数据进行分析，得到双星系统的质量比、轨道倾角、相接度等信息，研究双星系统的基本物理参量对O'Connell效应的影响。最后，综合分析磁活动、星周物质及物质交流在O'Connell效应形成和演化中扮演的角色，进而研究不同光谱型相接双星形成和演化上的联系与差异。

O'Connell效应即食双星光变曲线两极大值不等高现象，在相接双星光变曲线中比较常见。目前普遍认为O'Connell效应的形成主要与恒星活动、子星间的物质交流及星周物质有关。本项目基于LAMOST巡天、TESS巡天等释放的光谱和测光数据，结合地面光学望远镜，对一批具有O'Connell效应的相接双星进行了深入的观测分析。通过对O'Connell效应的统计研究，发现黑子和热斑均可导致O'Connell效应的形成。黑子主要是恒星活动引起的，而两子星间的物质交流对热斑的形成具有重要意义。揭示出在晚型相接双星中O'Connell效应普遍存在，而恒星活动是晚型相接双星O'Connell效应的主要形成机制。通过对PZ UMa等重要目标源的后续观测，发现了O'Connell效应在短时标内快速演化的特征，而这一显著特征与黑子的迁移活动密切相关。