标题： 关于小麦哲伦星系中Be/X射线双星的轨道参数 显示英文标题

标题： On the orbital parameters of Be/X-ray binaries in the Small Magellanic Cloud

摘要： 中子星围绕其光学伴星的轨道运动提供了一个窗口，用于研究该双星系统的轨道参数。这在银河系中被广泛用于计算几个高质量X射线双星系统的这些参数。利用几年的RXTE PCA数据，我们推导出小麦哲伦星系中四个Be/X射线双星系统的轨道参数，使具有轨道解的系统数量增加了三倍。我们发现了一个新的轨道周期，确认了第二个周期，并将这些参数与银河系系统进行了比较。尽管小麦哲伦星系的金属丰度较低，但这些双星系统位于银河系轨道周期和偏心率的分布范围内，表明金属丰度可能在高质量X射线双星系统的演化中并不起重要作用。轨道周期与偏心率的图表显示，超巨星、Be和低偏心率的OB暂现系统占据参数空间的不同区域；类似于Corbet图上的分离区域。通过Spearman等级相关检验，我们也发现这两个参数之间可能存在相关性。基于双星参数和光学伴星的光谱分类，推导出小麦哲伦星系系统的质量函数、倾角和轨道半长轴。作为我们工作的副产品，我们列出了银河系和麦哲伦云中每个高质量X射线双星的轨道参数目录，这些参数目前已知。 显示英文摘要

摘要： The orbital motion of a neutron star about its optical companion presents a window through which to study the orbital parameters of that binary system. This has been used extensively in the Milky Way to calculate these parameters for several high-mass X-ray binaries. Using several years of RXTE PCA data, we derive the orbital parameters of four Be/X-ray binary systems in the SMC, increasing the number of systems with orbital solutions by a factor of three. We find one new orbital period, confirm a second and discuss the parameters with comparison to the Galactic systems. Despite the low metallicity in the SMC, these binary systems sit amongst the Galactic distribution of orbital periods and eccentricities, suggesting that metallicity may not play an important role in the evolution of high-mass X-ray binary systems. A plot of orbital period against eccentricity shows that the supergiant, Be and low eccentricity OB transient systems occupy separate regions of the parameter space; akin to the separated regions on the Corbet diagram. Using a Spearman's rank correlation test, we also find a possible correlation between the two parameters. The mass functions, inclinations and orbital semimajor axes are derived for the SMC systems based on the binary parameters and the spectral classification of the optical counterpart. As a by-product of our work, we present a catalogue of the orbital parameters for every high-mass X-ray binary in the Galaxy and Magellanic Clouds for which they are known.