The VAST Survey - III. The multiplicity of A-type stars within 75 pc
The VAST Survey - III. The multiplicity of A-type stars within 75 pc
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VAST 调查 - III。
DOI：
10.1093/mnras/stt1932
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发表时间：
2014
影响因子：
4.8
通讯作者：
De Rosa R
中科院分区：
文献类型：
--
作者：
De Rosa R
结合自适应光学成像和多历元共同自行搜索，我们对A型星进行了大体积限制(D≤和75 PC)多重数测量，对30 Au以上的伴星很敏感。体积受限A星(Vavast)调查的样本由435颗A型恒星组成：363颗恒星使用自适应光学观测，228颗恒星寻找广泛的共同自行伴星，156颗恒星同时使用两种技术进行测量。这项庞大调查的预计离职覆盖面从30,000 Au延伸到45,000 Gbps Au。共分辨了包括在内的137个恒星伴星，并测量了伴星分数、投影分离分布和质量比分布。分离分布形成类似于太阳型二元分布的对数正态分布，但峰值向更宽的值移动。将拟合与30-10000Au观测范围内的分布进行积分，A型星的伴星比例估计为33.8%±22.6% %。较近(~lt；125Au)双星的质量比分布不同于较宽双星的质量比分布，较近双星的质量比分布平坦，较宽双星的质量比分布趋于较小。将这一结果与之前对A型恒星的光谱调查相结合，估计总伴星比例为68.9%±37.0% %。对高阶倍数的最完整评估是从大量样本的156颗恒星子集中估计出来的，其中既有自适应光学测量，又有共同的自行测量，再加上对伴星的彻底文献搜索，得出了单星、双星、三星、四星和五星A型恒星系统的频率下限分别为、和% CENT。
With a combination of adaptive optics imaging and a multi-epoch common proper motion search, we have conducted a large volume-limited (D≤ 75 pc) multiplicity survey of A-type stars, sensitive to companions beyond 30 au. The sample for the Volume-limited A-STar (VAST) survey consists of 435 A-type stars: 363 stars were observed with adaptive optics, 228 stars were searched for wide common proper motion companions and 156 stars were measured with both techniques. The projected separation coverage of the VAST survey extends from 30 to 45 000 au. A total of 137 stellar companions were resolved, including 64 new detections from the VAST survey, and the companion star fraction, projected separation distribution and mass ratio distribution were measured. The separation distribution forms a log-normal distribution similar to the solar-type binary distribution, but with a peak shifted to a significantly wider value ofau. Integrating the fit to the distribution over the 30 to 10 000 au observed range, the companion star fraction for A-type stars is estimated as 33.8 ± 2.6 per cent. The mass ratio distribution of closer (<125 au) binaries is distinct from that of wider systems, with a flat distribution for close systems and a distribution that tends towards smaller mass ratios for wider binaries. Combining this result with previous spectroscopic surveys of A-type stars gives an estimate of the total companion star fraction of 68.9 ± 7.0 per cent. The most complete assessment of higher order multiples was estimated from the 156 star subset of the VAST sample with both adaptive optics and common proper motion measurements, combined with a thorough literature search for companions, yielding a lower limit on the frequency of single, binary, triple, quadruple and quintuple A-type star systems of,,,andper cent, respectively.
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