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arXiv 1404.6576astro-ph.SR
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疏散星团中三个三星系统的动力学探测

Dynamical detection of three triple stellar systems in open clusters

J. F. Gonzalez, M. E. Veramendi, C. R. Cowley

摘要:

本文对NGC 2516中的CPD-60°961和HD 66137以及NGC 6530中的HD 315031这两个疏散星团中的三个三星系统进行了运动学分析。所有这三个系统都是层次三元组,其中一个紧密的二进制绑定到第三个机构在一个更广泛的轨道,其存在是通过检测的速度变化的紧密的二进制重心。轨道参数由径向速度曲线导出。所有恒星的绝对参数估计假设集群成员。一些动力学和演化方面的这些系统进行了讨论,特别是可能的影响Kozai周期。NGC 2516的两个系统具有相似的轨道构型,内周期分别为11.23 d和8.70 d,外周期分别为9.79 yr和9.24 yr。我们还报告了NGC 2516中CPD-60°944视双星各分量的径向速度测量结果。包括从以前的作品的结果,这个集群将窝藏5个层次三元组。年轻系统HD 315031有一个周期为1.37 d的内双星和一个周期为483 d的非常偏心(e=0.85)的外轨道。可能的动态演化的情况进行了讨论。长期的径向速度监测被强调为战略的检测子系统的中间分离,这是很难覆盖与正常的光谱研究或视觉技术。

英文摘要:

We present a kinematic analysis of three triple stellar systems belonging to two open clusters: CPD-60°961 and HD66137 in NGC2516, and HD315031 in NGC6530. All three systems are hierarchical triples with a close binary bound to a third body in a wider orbit, whose presence is detected through velocity variations of the close binary barycentre. Orbital parameters are derived from radial velocity curves. Absolute parameters for all stars are estimated assuming cluster membership. Some dynamical and evolutionary aspects of these systems are discussed, particularly the possible influence of Kozai cycles. The two systems of NGC2516 have similar orbital configurations with inner periods of 11.23 d and 8.70 d and outer periods of 9.79 yr and 9.24 yr. We report also radial velocity measurements of the components of the visual binary CPD-60°944 in NGC2516. Including results from previous works, this cluster would harbor 5 hierarchical triples. The young system HD315031 has an inner binary with a period of 1.37 d and a very eccentric (e=0.85) outer orbit with a period of 483 d. Possible dynamical evolutionary scenarios are discussed. Long-term radial velocity monitoring is highlighted as strategy for the detection of subsystems with intermediate separations, which are hard to cover with normal spectroscopic studies or visual techniques.

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