arXiv 1009.45962010-09astro-ph.SR

太阳附近星族II场星的多重数和周期分布

Multiplicity and period distribution of Population II field stars in solar vicinity

D. A. Rastegaev

备注：: 51 pages, 11 figures, accepted to AJ
DOI：: 10.1088/0004-6256/140/6/2013

摘要：

我们研究了223颗F、G和早期K贫金属亚矮星（[m/H]<-1）的样本，它们具有高自行（$μ> 0.2"/$年），距离太阳250 pc。通过在俄罗斯科学院特殊天体物理观测台的6米BTA望远镜上进行的散斑干涉观测，以及从文献中获得的光谱和视觉数据，我们确定了该样品中二元和多元系统的频率。在221个主要组分中，单组分、双组分、三组分和四组分的比例为147：64：9：1。我们发现，双和多重亚矮星的轨道周期的分布是不对称的范围内的$P=10^{10}$天，并有一个最大值在$P=10^{2}-10^{3}$天，什么不同的分布，薄盘G矮星（Duquennoy和市长1991年）。我们估计了样本中未被发现的同伴的数量。通过比较场和球状星团中次矮星双星的出现频率，我们发现在我们的银河系中，通过破坏球状星团而形成晕场星的过程是不可能的。我们讨论了在附近的恒星流的老贫金属恒星的多样性。

英文摘要：

We examine a sample of 223 F, G and early K metal-poor subdwarfs ([m/H]<-1) with high proper motions ($μ> 0.2"/$ year) at the distances of up to 250 pc from the Sun. By means of our own speckle interferometric observations conducted on the 6 m BTA telescope of the Special Astrophysical Observatory of the Russian Academy of Sciences, and the spectroscopic and visual data taken from the literature, we determine the frequency of binary and multiple systems in this sample. The ratio of single, binary, triple and quadruple systems among 221 primary components of the sample is 147:64:9:1. We show that the distribution of orbital periods of binary and multiple subdwarfs is asymmetric in the range of up to $P=10^{10}$ days, and has a maximum at $P=10^{2}-10^{3}$ days, what differs from the distribution, obtained for the thin disc G dwarfs (Duquennoy & Mayor 1991). We estimated the number of undetected companions in our sample. Comparing the frequency of binary subdwarfs in the field and in the globular clusters, we show that the process of halo field star formation by the means of destruction of globular clusters is very unlikely in our Galaxy. We discuss the multiplicity of old metal-poor stars in nearby stellar streams.

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