沃尔夫-拉叶双星及其星风碰撞活动

Wolf-Rayet Binaries and Their Wind-colliding Activities

作为进入演化晚期的大质量恒星,沃尔夫-拉叶星存在强烈的星风流失。如果沃尔夫-拉叶星与另一颗大质量恒星组成双星系统,双星的星风会互相碰撞形成星风碰撞双星系统,在星风碰撞区域会产生非热辐射。目前已有多个确认为沃尔夫-拉叶双星的射电源,其中如WR140,WR146,WR147已有较详细的射电干涉仪观测,发现了星风碰撞活动;另外还有一批沃尔夫-拉叶双星如WR105等是可能的星风碰撞双星候选体。比起一般的星际介质环境,星风碰撞区的物质密度、辐射流量以及磁场强度均较高,粒子在这一区域更容易受激获得能量并产生非热辐射,因而更适合研究粒子加速和产生辐射的机制。另外由于星风碰撞区的活动与双星活动和演化紧密相关,研究星风碰撞区也可以帮助研究大质量恒星的晚期演化。然而目前对星风碰撞双星系统的研究仍然匮乏,只有WR140建立了较完备的物理模型。文章简要介绍了沃尔夫-拉叶双星系统及其星风碰撞区的研究进展,特别是近年来射电干涉仪对于星风碰撞系统观测研究的主要贡献。

As high-mass stars in the end stage of evolution,Wolf-Rayet stars evolve with a significant mass loss due to strong stellar wind.For a binary system formed by a Wolf-Rayet star and a high-mass companion,stellar wind-colliding could result in a colliding-wind binary(CWB)system.And the radiation in wind-colliding region(WCR)is mainly dominated by nonthermal radio radiation.On the one hand,there are several radio sources identified as Wolf-Rayet binaries,such as WR140,WR146 as well as WR147,have been studied widely by radio interferometry technique,finding the stellar wind interactions among these systems.On the other hand,Wolf-Rayet stars such as WR105 may be a candidate of CWB system.Compared with general interstellar medium environment,the density of matter,flux density and magnetic field in WCR are much higher,as a result,particles in this region could obtain much more energy and produce nonthermal radiation,which provide us an extraordinary chance to study how the particles get accelerated and radiated.Moreover,there is a close connection between the activities of WCR and evolutions of binary systems,we can also investigate the final evolution of massive stars by studying the WCR.However,only a handful of results associated with CWB systems are published,and a special attention is given to WR140 predominantly due to a complete physical model has been established on it.In this context,we briefly introduce the research background of WR binary systems and their stellar wind collision activities,especially the contributions of radio interferometer observations on CWBs in recent years.