SUBSYSTEMS IN NEARBY SOLAR-TYPE WIDE BINARIES
SUBSYSTEMS IN NEARBY SOLAR-TYPE WIDE BINARIES
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附近太阳型宽双星中的子系统
DOI：
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发表时间：
2010
期刊：
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通讯作者：
T. Hayward
中科院分区：
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作者：
A. Tokovinin;M. Hartung;T. Hayward
我们在距太阳67pc的广角双星中对太阳类成分的分解的子系统进行了深入的调查。用8米双子座南望远镜上的近红外日冕成像仪自适应光学仪器获得了61颗恒星在K和H波段的图像。在0.“15”和0.9的间隔下，我们的最大可探测星等差分别为5 和7.8mag。这使得能够对具有恒星伴星的子系统进行完整的普查，所预测的分离范围从5到100 AU。在我们的样本中发现的七个这样的同伴中，只有一个是以前已知的。我们确定投影间隔大于5AU的子系统的比例为0.12±0.04，它们的质量比分布是平坦的，其幂指数为0.2±0.5。与较近的光谱子系统(分离小于1AU)的性质相比较，似乎质量比分布并不依赖于分离。分离带中各亚系的分布频率在1 AU以下和5-100 AU之间相似，约为0.15。这项工作提出的重数大于2的无偏统计为恒星形成理论提供了约束。
We conducted a deep survey of resolved subsystems among wide binaries with solar-type components within 67 pc of the Sun. Images of 61 stars in the K and H bands were obtained with the Near-Infrared Coronagraphic Imager adaptive-optics instrument on the 8 m Gemini-South telescope. Our maximum detectable magnitude difference is about 5 mag and 7.8 mag at 0.″15 and 0.″9 separations, respectively. This enables a complete census of subsystems with stellar companions in the projected separation range from 5 to 100 AU. Out of seven such companions found in our sample, only one was previously known. We determine that the fraction of subsystems with projected separations above 5 AU is 0.12 ± 0.04 and that the distribution of their mass ratio is flat, with a power-law index of 0.2 ± 0.5. Comparing this with the properties of closer spectroscopic subsystems (separations below 1 AU), it appears that the mass-ratio distribution does not depend on the separation. The frequency of subsystems in the separation ranges below 1 AU and between 5 and 100 AU is similar, about 0.15. Unbiased statistics of multiplicity higher than 2, advanced by this work, provide constraints on star formation theory.