The LuckyCam survey for very low mass binaries - II. 13 new M4.5-M6.0 binaries
The LuckyCam survey for very low mass binaries - II. 13 new M4.5-M6.0 binaries
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DOI：
10.1111/j.1365-2966.2007.12675.x
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发表时间：
2007-04
影响因子：
4.8
通讯作者：
N. Law;S. Hodgkin;C. Caltech;Ioa;Cambridge
中科院分区：
文献类型：
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作者：
N. Law;S. Hodgkin;C. Caltech;Ioa;Cambridge
我们给出了对77个极低质量（VLM）双星系统的高角分辨率调查的结果，这些系统6.0≤V - K色≤7.5，固有运动≥0.15 arcsec yr^（-1）。共探测到21个VLM双星，其中13个是新发现的。新的双星系统的距离在0.18到1.3弧秒之间。距离校正后的二进制分数为13.6(-4)(+ 6.5%)，与先前的结果一致。其中9个新双星系统的预计轨道距离为1010au，包括一个新的宽VLM双星系统，预计轨道距离为27au。其中一个新系统形成了2300 au分离三重系统的两个组成部分。我们发现，在这次调查中，V - K < 6.5的双星的投影分离分布似乎与较红（质量较低）的天体不同，这表明在M5光谱型周围的轨道半径分布可能发生了快速变化。还选择了目标样品来研究VLM双星之间的x射线活性。过量x射线发射与VLM系统的频率和二元特性之间没有可检测到的相关性。
We present results from a high angular resolution survey of 77 very low mass (VLM) binary systems with 6.0 ≤ V - K colour ≤ 7.5 and proper motion ≥ 0.15 arcsec yr^(-1). 21 VLM binaries were detected, 13 of them new discoveries. The new binary systems range in separation between 0.18 and 1.3 arcsec. The distance-corrected binary fraction is 13.6(-4)(+6.5) per cent, in agreement with previous results. Nine of the new binary systems have projected separations > 10 au, including a new wide VLM binary with 27 au projected orbital separation. One of the new systems forms two components of a 2300 au separation triple system. We find that the projected separation distribution of the binaries with V - K < 6.5 in this survey appears to be different from that of redder (lower mass) objects, suggesting a possible rapid change in the orbital radius distribution at around the M5 spectral type. The target sample was also selected to investigate X-ray activity among VLM binaries. There is no detectable correlation between excess X-ray emission and the frequency and binary properties of the VLM systems.