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arXiv 0912.0735astro-ph.SR
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用棕矮星双星检验模型

Testing Models with Brown Dwarf Binaries

Trent J. Dupuy, Michael C. Liu

备注：
Proceedings of IAU 2009 SpS7: "Young Stars, Brown Dwarfs, and Protoplanetary Disks"
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摘要：

我们一直在使用凯克激光导星自适应光学来监测超冷双星的轨道，在比以前更低的光度和温度下提供动态质量，并对理论模型进行强有力的测试。(1)我们发现，模型颜色星等图不能可靠地用来推断质量，因为它们不能准确地再现已知质量的超冷矮星的颜色。(2)从演化模型半径推断出的有效温度可能与通过将观测光谱与大气模型拟合得出的温度不一致，最多不一致100-300 K。(3)对于具有精确质量（3%）和年龄测定（~25%）的单对褐矮星，测量的光度比模型冷却速率预测的高2- 3倍（从Lbol和年龄推断的质量比测量的大20-30%）。最后，随着具有测量轨道的双星样本的增长，褐矮星形成理论的新测试成为可能（例如，测试理论偏心率分布）。

英文摘要：

We have been using Keck laser guide star adaptive optics to monitor the orbits of ultracool binaries, providing dynamical masses at lower luminosities and temperatures than previously available and enabling strong tests of theoretical models. (1) We find that model color-magnitude diagrams cannot reliably be used to infer masses as they do not accurately reproduce the colors of ultracool dwarfs of known mass. (2) Effective temperatures inferred from evolutionary model radii can be inconsistent with temperatures derived from fitting observed spectra with atmospheric models by at most 100-300 K. (3) For the single pair of field brown dwarfs with a precise mass (3%) and age determination (~25%), the measured luminosities are ~2-3x higher than predicted by model cooling rates (masses inferred from Lbol and age are 20-30% larger than measured). Finally, as the sample of binaries with measured orbits grows, novel tests of brown dwarf formation theories are made possible (e.g., testing theoretical eccentricity distributions).

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