G型相接双星磁场活动的观测与研究

Solar-like magnetic activity is one of the hot and difficult issues in astrophysics. Based on the monitoring and analysis of close binaries, many researchers found evidences of sunspot and flare on the surface of most components, but there is still a lack of magnetic activity and its regularity in close binaries. The target of this project is G-type contact binary. Compared with the rotational period of 24.6 days as the sun, the rotation of the G-type components in contact binaries are about 60～100 times of that of the sun. According to the stellar dynamo theory, there may be much stronger magnetic activities on the surface of the components than that on the sun, which provides a good opportunity for us to investigate on magnetic activity in detail. This project makes full use of domestic medium and small aperture telescopes, international open telescope resources to monitor them, and obtain their complete light curves in different times. Through analysis of light curves, we will derive their basic physical parameters. Then, we discuss the individuality and commonness of the magnetic activity of the components in G-type contact binaries, and explore the correlation between magnetic activities and common convective envelope, or orbital period variations.

恒星类太阳活动是天体物理学中研究热点和难点之一。研究者们依据对密近双星的监测和分析，发现大部分子星表面存在黑子、耀斑等类太阳磁场活动的证据，但是对双星系统中子星表面磁场活动及规律的认识仍不足。本项目的研究对象为G型相接双星，与太阳24.6天的自转周期相比，G型相接双星的两子星自转速度约为太阳的60～100倍。根据磁发电机理论，该类系统中的子星表面可能存在比太阳强烈得多的磁场活动，这为我们深入细致地研究磁场活动及规律提供了非常好的机会。本项目依托国内众多中小口径望远镜，充分利用国际上的开放望远镜资源，对一批样本星进行长期监测，得到它们不同时期完整的光变曲线。并对光变曲线进行求解分析，获得它们的基本物理参数，探讨G型相接双星中的子星磁场活动的个性与共性，探究磁场活动与公共包层、轨道周期变化的相关性。

G型相接双星系统中，两颗子星内部深层对流中存在较差自转，自转速度越快，表面磁场活动越强烈。该类系统测光研究中，光变曲线的O’Connell效应可作为磁场活动的直接证据，同时通过测光解轨道分析G型相接双星存在A次型和W次型的转换，这一现象是恒星磁场活动变化的直接作用结果。项目统计一批G型相接双星样本物理信息（轨道倾角、相接度、温度、周期、质量比、轨道周期变化、第三天体等），初步建立G型详解双星信息库，分析得到：W次型和浅度相接双星磁场活动较为剧烈，存在第三天体的数目较多。项目通过国内外中小型和Tess巡天望远镜获得HH Boo, V680 Per, UV Lyn, TU Boo, EF Boo, FG Hya, EQ Tau, 1SWASP J204932.94-654025.8和1SWASP J034439.97+030425.5等观测数据并分析，利用WD测光解轨方法和轨道周期变化分析，我们得到了这些双星系统的基本把物理参数以及磁场活动情况。通过对比分析，讨论了单个样本星的个性与多个样本星的共性，推测结果为：浅度相接双星的磁场活动较为强烈，而磁场活动与轨道周期变化不存在相关性，轨道周期的周期性变化大多源于第三天提的光时轨道效应；磁场活动随着时间表现出circle-to-circle连续变化。