DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XI. V1191 CYGNI
DEEP, LOW MASS RATIO OVERCONTACT BINARY SYSTEMS. XI. V1191 CYGNI
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DOI：
10.1088/0004-6256/142/4/124
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发表时间：
2011-10
期刊：
影响因子：
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通讯作者：
Li-ying Zhu;S. Qian;B. Soonthornthum;J. He;Long-xiang Liu
中科院分区：
文献类型：
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作者：
Li-ying Zhu;S. Qian;B. Soonthornthum;J. He;Long-xiang Liu
给出了2009年某夜获得的短周期密近双星V1191 Cygni在BV（RI）c波段的完整CCD测光光变曲线。采用2003年版本的Wilson-Van Hamme程序对V1191 Cyg进行的光度分析表明，它是一个W型过接触双星系统，具有很高的过接触度（f = 68.6%）和很低的质量比，表明它处于过接触演化的晚期。V1191 Cyg的绝对参数是使用光谱和光度的解决方案。结合新测得的光极小时刻和文献中已发表的光极小时刻，研究了双星星星的周期变化。一个周期为26.7年，振幅为0.023天的周期性变化被发现叠加在一个长期的周期增加上（dP/dt = +4.5（± 0.1）× 10−7天yr−1）。这种周期振荡可能是由两个组成部分的磁活动周期引起的，也可能是由质量为m3 = 0.77 M、轨道半径为a3 = 7.6 Au的第三个天体与食对轨道共面时的光时效应引起的。长期轨道周期的增加可以解释为从质量较小的组分到质量较大的组分的质量转移。随着周期的增加，当V1191的轨道角动量小于总自旋角动量的3倍时，它将从目前的低质量比、高填充的过接触态演化为快速旋转的单颗星星. V1191 Cyg对于它的轨道周期来说太蓝了，它是一个不寻常的W型过接触系统，具有如此低的质量比和高的填充过接触构型，值得未来继续监测。
Complete CCD photometric light curves in BV(RI)c bands obtained on one night in 2009 for the short-period close-binary system V1191 Cygni are presented. A new photometric analysis with the 2003 version of the Wilson–Van Hamme code shows that V1191 Cyg is a W-type overcontact binary system and suggests that it has a high degree of overcontact (f = 68.6%) with very low mass ratio, implying that it is at the late stage of overcontact evolution. The absolute parameters of V1191 Cyg are derived using spectroscopic and photometric solutions. Combining new determined times of light minimum with others published in the literature, the period change of the binary star is investigated. A periodic variation, with a period of 26.7 years and an amplitude of 0.023 days, was discovered to be superimposed on a long-term period increase (dP/dt = +4.5(± 0.1) × 10−7 days yr−1). The cyclic period oscillation may be caused by the magnetic activity cycles of either of the components or the light-time effect due to the presence of a third body with a mass of m3 = 0.77 M☉ and an orbital radius of a3 = 7.6 AU, when this body is coplanar to the orbit of the eclipsing pair. The secular orbital period increase can be interpreted as a mass transfer from the less massive component to the more massive one. With the period increases, V1191 Cyg will evolve from its present low mass ratio, high filled overcontact state to a rapidly rotating single star when its orbital angular momentum is less than three times the total spin angular momentum. V1191 Cyg is too blue for its orbital period and it is an unusual W-type overcontact system with such a low mass ratio and high fill-out overcontact configuration, which is worth monitoring continuously in the future.