双星与变星研究组知识库

化学组成特殊星(即CP星)是一类具有特殊化学元素丰度的恒星,大部分属于A型和B型主序星。主要介绍了CP星的分类、特征以及主要的起源理论。CP星存在于双星中的比例非常高,在Am星和Hg-Mn星中双星的比例高达90%以上。当CP星是食双星的成员时,通过对双星的观测可以精确地确定CP星的质量、半径等物理参数;双星中物质交流以及最终的子星并合等也可能会形成CP星的特殊化学组成和强磁场。通过CP星双星的观测与研究,有助于研究CP星的起源和演化,也为解释CP现象提供了一个有效途径。

Chemically peculiar stars (CP star) are the stars in the spectra of which lines of some elements are abnormally strong or weak. Most of them are main sequence A and B type stars. By now, the research of the CP star also is very little in China. In the present paper, we introduce the characteristics, classification and main original theories of CP stars. At the same time,a detailed introduction of the mainly subclasses of the CP stars is given, such as Am star,Hg-Mn star,magnetic CP star and so on. Strong magnetic filed has been found in CP star(magnetic CP star), but not all CP star are magnetic CP star.For Am star and Hg-Mn star, just weak magnetic field (2×10⁻⁵ T) or no magnetic filed was detected. The origin of CP star still is a problem for us.Even though there are many theories trying to explore it, no one is totaly accurate so far. The percentage of CP stars in the binaries is really high. For example, 90% Am and Hg-Mn stars are in the binary systems, and for Ap and Bp star,the percentage is 43% and 20% respectively. The binary environment provides abundant information of CP star, especially when the CP star is a component of an eclipsing binary, many important physical quantities, such as mass and radius, can be determined in high precision. In addition, the mass transfer and the stellar merger happened in the binary systems may be the main reasons which cause the peculiar elements abundance and form the strong magnetic field in the CP stars. Therefore, the study of the CP-star binaries are particularly important for understanding the formation and evolution of this special objects. In the future, The systematic investigation of the CP-star binaries and the progenitor binaries of CP stars will be a crucial way to reveal the nature of the CP phenomenon.