双星与变星研究组知识库

矮新星是爆发频繁的激变变星,主星是白矮星,次星是充满洛希瓣的晚型矮星;白矮星周围有吸积盘,物质流与吸积盘的碰撞区域即热斑。与大多数密近双星系统相比,矮新星最大的特点是吸积盘的存在以及频繁的爆发现象。首先介绍了矮新星的研究历史和现状,对吸积盘的形成过程进行总结,给出了矮新星的基本物理图像;其次简要介绍了矮新星的各种次型的特征和形成原因,对目前的爆发模型进行归纳;回顾了矮新星中著名的轨道周期空缺现象和最短轨道周期截止现象,并给出其在标准化模型下的解释以及标准化模型面临的挑战;举例说明了矮新星的轨道周期变化分析不仅对研究其演化起着重要作用,而且是探测褐矮星和地外行星的重要手段;对食光变曲线的分析方法和矮新星中罕见的高低态变化进行了简单小结;最后,进行总结并讨论矮新星领域的发展趋势和目前的一些热点问题。

Dwarf novae are erupting cataclysmic variable stars in which a Roche-lobe filling dwarf star (Secondary star) transfers matter to an accretion disc around a white dwarf (Primary star). The gas stream from the secondary star feeds material into the disc at a point near its outer rim where a bright spot is formed. The existence of accretion disc induces complex physical changes and observed features, including the frequent outburst phenomenon and the transitions from high states to low states, etc. The eclipse between binary stars provides an excellent opportunity to determine the relative brightness of each light source, geometric position and physical structure. Compared to most close binary systems, the largest characteristic of dwarf novae are the existence of accretion disc and the frequent outburst phenomenon. First, we give a brief review of the research history and status of dwarf novae studies. Second, the famous phenomenon of the orbital period vacancy and the cut-off of the shortest orbital period are reviewed, where their explanations and challenges on the standard model are presented in general. Then, the orbital period variability is demonstrated to have important role on the research of its evolution, as well as on searching brown dwarf and exoplanet. In addition, the analysis method of the eclipsing light curve and altering between the high and low state are briefly discussed. Finally, we give a brief summary on the development trend and the currently hot issues on the sub ject of dwarf novae.