An Adaptive Optics Survey of M8-M9 Stars: Discovery of Four Very Low Mass Binaries with at Least One System Containing a Brown Dwarf Companion
An Adaptive Optics Survey of M8-M9 Stars: Discovery of Four Very Low Mass Binaries with at Least One System Containing a Brown Dwarf Companion
复制标题
M8-M9 恒星的自适应光学巡天：发现四颗极低质量双星，其中至少有一个系统包含褐矮星伴星
DOI：
10.1086/339795
复制
发表时间：
2002
期刊：
影响因子：
--
通讯作者：
J. Liebert
中科院分区：
文献类型：
--
作者：
L. Close;N. Siegler;D. Potter;W. Brandner;J. Liebert
使用高灵敏度的Hokupa 'a/Gemini曲率波前传感器，首次允许对M8-M9极低质量（VLM）恒星进行直接自适应光学制导。对20个这样的天体（光谱类型= M8-M9）的初步调查发现了四个双星。其中三个系统的分离度小于4.2 Au，质量比相似（ΔK < 0.8 mag; 0.85 < q < 1.0）。然而，有一个系统确实有最大的质量比（ΔK = 2.38等）和分离（14.4 Au），这是迄今为止观测到的VLM星星与棕矮星伴星的最大质量比。根据我们对20颗M8-M9恒星在14 h26 m <R. A. Gizis等人的样品<4 h30 m，我们发现，在距离小于3 Au的M8-M9双星中，双星分数在14%-24%的范围内。这可能与在相同的分离范围内测量到的更大质量（M0-M6）恒星的23% ± 5%一致。与M和G星相比，M8-M9双星的半长轴分布峰似乎要小得多（约4 Au;没有系统宽于15 Au），M和G星在更大的约30 Au间距处有一个宽峰。
Use of the highly sensitive Hokupa'a/Gemini curvature wave-front sensor has allowed, for the first time, direct adaptive optics guiding on M8-M9 very low mass (VLM) stars. An initial survey of 20 such objects (spectral type = M8-M9) discovered four binaries. Three of the systems have separations of less than 4.2 AU and similar mass ratios (ΔK < 0.8 mag; 0.85 < q < 1.0). One system, however, did have the largest mass ratio (ΔK = 2.38 mag) and separation (14.4 AU) yet observed for a VLM star with a brown dwarf companion. Based on our initial flux-limited (Ks < 12 mag) survey of 20 M8-M9 stars over 14h26m < R.A. < 4h30m from the sample of Gizis et al., we find a binary fraction in the range of 14%-24% for M8-M9 binaries with separations of less than 3 AU. This is likely consistent with the 23% ± 5% measured for more massive (M0-M6) stars over the same separation range. It appears that M8-M9 binaries have a much smaller semimajor axis distribution peak (~4 AU; with no systems wider than 15 AU) compared with M and G stars that have a broad peak at larger ~30 AU separations.
影响因子：
3.2
作者：
V. Mannings;A. Boss;S. Russell
通讯作者：
V. Mannings;A. Boss;S. Russell