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Nearby Quintuple Systems κ Tucanae and ξ Scorpii
The Astronomical Journal ( IF 5.1 ) Pub Date : 2020-05-18 , DOI: 10.3847/1538-3881/ab8af1
Andrei Tokovinin

Architecture and parameters of two wide nearby hierarchical systems containing five solar-type stars each, $\kappa$ Tuc and $\xi$ Sco, are studied. Using Gaia astrometry and photometry, masses are determined from visual orbits and isochrones, effective temperatures from spectra or colors. Both systems are ~2 Gyr old. Their spatial motion corresponds to young disk but does not match any known kinematic group. Internal proper motions relative to the center of mass and radial velocities show that wide ~8 kau outer pairs are bound. No correlation between orbit orientations in the inner subsystems is observed. All masses except one are confined to the narrow range from 0.8 to 1.5 solar. Strongly correlated masses and wide orbits can be explained if those systems formed by fragmentation in relative isolation and their components accreted gas from common source, as expected in a hierarchical collapse. Young moving groups could be formed in similar environments, and many of them contain high-order hierarchies.

中文翻译:

附近的五重系统 κ Tucanae 和 ξ Scorpii

研究了两个广泛的邻近等级系统的结构和参数,每个系统包含五颗太阳型恒星,$\kappa$ Tuc 和 $\xi$ Sco。使用盖亚天体测量法和光度测量法,质量是根据视觉轨道和等时线确定的,有效温度来自光谱或颜色。两个系统都是 ~2 Gyr 旧。它们的空间运动对应于年轻的磁盘,但不匹配任何已知的运动组。相对于质心和径向速度的内部适当运动表明,宽~8 kau 外对是束缚的。没有观察到内部子系统中轨道方向之间的相关性。除了一个质量之外,所有质量都被限制在 0.8 到 1.5 太阳的狭窄范围内。如果那些由相对孤立的碎片形成的系统及其组成部分从共同来源吸积气体,如分层坍塌中所预期的那样,则可以解释强相关的质量和宽轨道。年轻的移动群体可以在类似的环境中形成,其中许多包含高阶层次结构。
更新日期:2020-05-18
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