SW六分仪星：轨道周期在3-4小时之间的CV的主要群体
SW Sextantis stars: the dominant population of CVs with orbital periods between 3-4 hours
摘要：
[摘要]我们提出了汉堡类星体巡天发现的五个新CV的时间序列光学光度学。在HS 0129+2933、HS 0220+0603和HS 0455+8315中观测到的日食提供了非常精确的轨道周期，分别为3.35129827（65）、3.58098501（34）和3.56937674（26）h。HS 0805+3822显示掠食，轨道周期可能为3.2169（2）h。还提供了新CV（HS 0805+3822除外）的时间分辨光谱。径向速度研究提供了HS 1813+6122的轨道周期为3.55小时，这使我们能够确定在3.39小时观测到的光度信号为负超级驼峰波。光谱行为清楚地将这些新的CV确定为新的SW六分仪星。这些新的增加增加了已知的SW性明星的数量到35。几乎40%的SW Sex人口没有显示日食，使日食作为该类别的定义特征的要求无效，并且仅基于高轨道倾角几何形状的模型。另一方面，轨道周期在3-4.5小时狭窄范围内的优势越来越明显。事实上，几乎一半的CV填充3-4.5小时的周期间隔是类的明确成员。这些统计数据得到了我们从汉堡类星体巡天CV得到的结果的证实。值得注意的是，54%的汉堡新星类变星被确定为SW性星，轨道周期在3-4.5小时范围内。这种靠近周期间隙上边界的堆积系统的观测结果很难与CV演化的标准理论相一致，因为SW性星被认为具有CV中最高的质量传递速率。最后，我们回顾了所有的共同属性，SW性明星的展览。
英文摘要：
[Abridged] We present time-series optical photometry of five new CVs identified by the Hamburg Quasar Survey. The eclipses observed in HS 0129+2933, HS 0220+0603, and HS 0455+8315 provided very accurate orbital periods of 3.35129827(65), 3.58098501(34), and 3.56937674(26) h, respectively. HS 0805+3822 shows grazing eclipses and has a likely orbital period of 3.2169(2) h. Time-resolved optical spectroscopy of the new CVs (with the exception of HS 0805+3822) is also presented. Radial velocity studies provided an orbital period of 3.55 h for HS 1813+6122, which allowed us to identify the observed photometric signal at 3.39 h as a negative superhump wave. The spectroscopic behaviour clearly identifies these new CVs as new SW Sextantis stars. These new additions increase the number of known SW Sex stars to 35. Almost 40 per cent of the total SW Sex population do not show eclipses, invalidating the requirement of eclipses as a defining characteristic of the class and the models based on a high orbital inclination geometry alone. On the other hand, the predominance of orbital periods in the narrow 3-4.5 h range is becoming more pronounced. In fact, almost half the CVs which populate the 3-4.5 h period interval are definite members of the class. These statistics are confirmed by our results from the Hamburg Quasar Survey CVs. Remarkably, 54 per cent of the Hamburg nova-like variables have been identified as SW Sex stars with orbital periods in the 3-4.5 h range. The observation of this pile-up of systems close to the upper boundary of the period gap is difficult to reconcile with the standard theory of CV evolution, as the SW Sex stars are believed to have the highest mass transfer rates among CVs. Finally, we review the full range of common properties that the SW Sex stars exhibit.
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