ε Indi Ba,Bb: The nearest binary brown dwarf
ε Indi Ba,Bb: The nearest binary brown dwarf
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ε Indi Ba,Bb：最近的双星褐矮星
DOI：
10.1051/0004-6361:20034292
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发表时间：
2003
影响因子：
6.5
通讯作者：
Chile.
中科院分区：
文献类型：
--
作者：
M. McCaughrean;L. Close;R. Scholz;R. Lenzen;B. Biller;W. Brandner;M. Hartung;N. A. I. Potsdam;H Germany;S. Observatory;Tucson;Usa;Max;Heidelberg;E. Observatory;Santiago;Chile.
我们已经进行了高角分辨率近红外成像和低分辨率（$R\sim1000$）光谱最近的已知棕矮星，e Indi B，使用ESO VLT NAOS/CONICA自适应光学系统。我们发现它是一颗近距离双星（Volk et al. 2003也提到过），角距为0.732角秒，相当于2.65个Au，距离为3.626 pc。在我们的发现论文（Scholz et al. 2003）中，我们得出的结论是，e Indi B是一个约50 M Jup的T2.5矮星：我们修正的发现是，两个系统的组成部分（e Indi Ba和e Indi B B）分别有T1和T6的光谱类型，估计质量分别为47和28 M Jup，假设年龄为1.3 Gyr。质量误差分别为± 10和± 7兆焦耳，主要是年龄测定的不确定性（0.8-2吉耳范围）。这个独特的T型矮双星系统在低质量冷棕矮星的研究中应该是非常重要的。这两个组成部分都很明亮，并且相对来说分辨得很好：e Indi B是唯一一个同时获得这两个组成部分光谱的T型矮双星。该系统具有良好的距离和年龄。最后，它们的轨道运动可以在相当短的时间尺度上测量（标称轨道周期~15年），允许准确确定系统的真实总质量，有助于校准棕矮星演化模型。
We have carried out high angular resolution near-infrared imaging and low-resolution ($R\sim1000$) spectroscopy of the nearest known brown dwarf, e Indi B, using the ESO VLT NAOS/CONICA adaptive optics system. We find it to be a close binary (as also noted by Volk et al. 2003), with an angular separation of 0.732 arcsec, corresponding to 2.65 AU at the 3.626 pc distance of the e Indi system. In our discovery paper (Scholz et al. 2003), we concluded that e Indi B was a ~50 M Jup T2.5 dwarf: our revised finding is that the two system components ( e Indi Ba and e Indi Bb) have spectral types of T1 and T6, respectively, and estimated masses of 47 and 28 M Jup , respectively, assuming an age of 1.3 Gyr. Errors in the masses are ± 10 and ± 7 M Jup , respectively, dominated by the uncertainty in the age determination (0.8–2 Gyr range). This uniquely well-characterised T dwarf binary system should prove important in the study of low-mass, cool brown dwarfs. The two components are bright and relatively well-resolved: e Indi B is the only T dwarf binary in which spectra have been obtained for both components. The system has a well-established distance and age. Finally, their orbital motion can be measured on a fairly short timescale (nominal orbital period ~15 yrs), permitting an accurate determination of the true total system mass, helping to calibrate brown dwarf evolutionary models.