A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK Adaptive Optics Results from the Gemini Near-Infrared Imager
A High Angular Resolution Survey of Massive Stars in Cygnus OB2: JHK Adaptive Optics Results from the Gemini Near-Infrared Imager
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DOI：
10.3847/1538-3881/aba536
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发表时间：
2020-09-01
影响因子：
5.3
通讯作者：
Turner, N. H.
中科院分区：
文献类型：
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作者：
Caballero-Nieves, S. M.;Gies, D. R.;Turner, N. H.
我们目前的结果，大规模OB星的天鹅座OB 2协会，我们进行了近红外成像相机和ALTAIR自适应光学系统的双子座北望远镜的高角分辨率调查。我们观察了74 O-和早期的B-型星在天鹅座OB 2的JHK红外波段，以检测二进制和多个同伴。这些观测对等亮度的伴星在0“.08的小间距上是敏感的，而逐渐变暗的伴星在2”的间距上可以探测到Δ K = 9等。由于读取噪声导致的这种微弱的对比度限制在探测器边缘附近持续到10 "。我们根据每个伴星与中心目标星星的距离和星等差异，以及天鹅座OB 2一般星星场的面积星星计数，为每个伴星分配了一个简单的机会对齐概率。场成员概率小于1%的伴星被认为是物理伴星。这一评估表明，47%的目标至少有一个被解析的伴星，可能是引力束缚的。包括已知的光谱双星，我们的样本包括27个二进制，12个三重和9个系统与4个或更多的组件。这些结果证实了在其他环境中对大质量恒星的研究，这些研究发现大质量恒星出生时具有高多重性。这些结果对于恒星在赫兹-罗素图中的位置、光谱分析的解释以及未来通过测量轨道运动来确定质量都很重要。
We present results of a high angular resolution survey of massive OB stars in the Cygnus OB2 association that we conducted with the Near-Infrared Imager camera and ALTAIR adaptive optics system of the Gemini North telescope. We observed 74 O- and early-B-type stars in Cyg OB2 in the JHK infrared bands in order to detect binary and multiple companions. The observations are sensitive to equal-brightness pairs at separations as small as 0 ''.08, and progressively fainter companions are detectable out to Delta K = 9 mag at a separation of 2 ''. This faint contrast limit due to read noise continues out to 10 '' near the edge of the detector. We assigned a simple probability of chance alignment to each companion based upon its separation and magnitude difference from the central target star and upon areal star counts for the general star field of Cyg.OB2. Companion stars with a field membership probability of less than 1% are assumed to be physical companions. This assessment indicates that 47% of the targets have at least one resolved companion that is probably gravitationally bound. Including known spectroscopic binaries, our sample includes 27 binary, 12 triple, and 9 systems with 4 or more components. These results confirm studies of high-mass stars in other environments that find that massive stars are born with a high-multiplicity fraction. The results are important for the placement of the stars in the Hertzsprung-Russell diagram, the interpretation of their spectroscopic analyses, and for future mass determinations through measurement of orbital motion.