THE SOLAR NEIGHBORHOOD. XXVIII. THE MULTIPLICITY FRACTION OF NEARBY STARS FROM 5 TO 70 AU AND THE BROWN DWARF DESERT AROUND M DWARFS
THE SOLAR NEIGHBORHOOD. XXVIII. THE MULTIPLICITY FRACTION OF NEARBY STARS FROM 5 TO 70 AU AND THE BROWN DWARF DESERT AROUND M DWARFS
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DOI：
10.1088/0004-6256/144/2/64
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发表时间：
2012-06
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影响因子：
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通讯作者：
S. Dieterich;T. Henry;D. Golimowski;J. Krist;A. Tanner
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作者：
S. Dieterich;T. Henry;D. Golimowski;J. Krist;A. Tanner
我们报告我们的分析哈勃太空望远镜/NICMOS快照高分辨率图像的255颗恒星在201个系统内的太阳100 pc。使用NICMOS相机2通过滤光片F110 W、F180 M、F207 M和F222 M获得光度测定。选择这些滤光片是为了通过甲烷对比成像清晰地识别冷棕矮星。NICMOS的底片尺寸为76 mas pixel−1，可以在19.“5×19.”5的视场内轻松分辨亚弧秒间隔的双星。我们先前报告了从这次搜索中发现的附近M和L矮星的五个同伴。在第二阶段的数据分析中没有发现新的伴星，证实了恒星/亚恒星双星是罕见的。我们建立的星等和分离的限制，同伴可以排除每个星星的样本，然后进行全面的灵敏度和完整性分析的子样本的138 M矮星在126个系统。我们计算出在5-70 Au的距离范围内，M矮星的L伴星的多重性分数为0.0+3.5−0.0%，在10-70 Au的距离范围内，M矮星的L伴星和T伴星的多重性分数为2.3+5.0−0.7%。我们还讨论了使用各种颜色组合的颜色星等图的趋势，并在我们的样本中为19个多系统提供天体测量。考虑到这些结果和其他几项研究的结果，我们认为，所谓的棕矮星沙漠延伸到低质量的初级双星系统，在很大程度上是独立的初级质量，质量比，和分离。虽然专注于同伴的属性，我们讨论如何观察到的同伴质量函数和初始质量函数之间的定性协议表明，在任何人口的褐矮星的缺乏可能是由于一个共同的原因，而不是由于二进制的形成机制。
We report on our analysis of Hubble Space Telescope/NICMOS snapshot high-resolution images of 255 stars in 201 systems within ∼10 pc of the Sun. Photometry was obtained through filters F110W, F180M, F207M, and F222M using NICMOS Camera 2. These filters were selected to permit clear identification of cool brown dwarfs through methane contrast imaging. With a plate scale of 76 mas pixel−1, NICMOS can easily resolve binaries with subarcsecond separations in the 19.″5×19.″5 field of view. We previously reported five companions to nearby M and L dwarfs from this search. No new companions were discovered during the second phase of data analysis presented here, confirming that stellar/substellar binaries are rare. We establish magnitude and separation limits for which companions can be ruled out for each star in the sample, and then perform a comprehensive sensitivity and completeness analysis for the subsample of 138 M dwarfs in 126 systems. We calculate a multiplicity fraction of 0.0+3.5−0.0% for L companions to M dwarfs in the separation range of 5–70 AU, and 2.3+5.0−0.7% for L and T companions to M dwarfs in the separation range of 10–70 AU. We also discuss trends in the color–magnitude diagrams using various color combinations and present astrometry for 19 multiple systems in our sample. Considering these results and results from several other studies, we argue that the so-called brown dwarf desert extends to binary systems with low-mass primaries and is largely independent of primary mass, mass ratio, and separations. While focusing on companion properties, we discuss how the qualitative agreement between observed companion mass functions and initial mass functions suggests that the paucity of brown dwarfs in either population may be due to a common cause and not due to binary formation mechanisms.