WISE J104915 .57-531906.1AB的近红外分辨光谱：一个处于L矮星/T矮星转换的磁通量-反射双星
Resolved Near-Infrared Spectroscopy of WISE J104915.57-531906.1AB: A Flux-Reversal Binary at the L dwarf/T dwarf Transition
摘要：
我们报告了最近发现的褐矮星双星WISE J104915.57-531906.1AB的近红外光谱和测光，位于距离太阳2.02+/-0.15 pc。麦哲伦/FIRE和IRTF/SpeX的低分辨率光谱数据显示，两种组分的光谱中都有较强的H2O和CO吸收特征，次级组分在1.6微米和2.2微米处也有较弱的CH 4吸收。光谱指数和低分辨率光谱标准的比较表明L7.5和T0.5的组件类型，前者与小学的光学分类一致。相对光度测定法揭示了J-和K-波段之间的通量反转，其中T矮星分量在0.95- 1.3微米范围内更亮。与其他的L/T转换双星一样，这种反转可能反映了整个转换过程中凝结不透明度的显着减少，如果其L矮星组件的不寻常的红色指示厚云，则WISE J1049- 5319 AB的这种行为可能会增强。另一方面，不同的云属性可能已经修改了这两个组件的演化路径，我们提出了一个方案，其中较冷的次级可能是两个组件中更大的。幸运的是，这个系统的接近度、亮度和小的间隔（3.12+/-0.25 AU）使它在估计的25年轨道期间可以进行天体测量和径向速度轨道测量，这为直接确定单个棕矮星质量提供了难得的机会，也为研究L矮星/T矮星过渡期间的云演化提供了独特的基准。
英文摘要：
We report resolved near-infrared spectroscopy and photometry of the recently identified brown dwarf binary WISE J104915.57-531906.1AB, located 2.02+/-0.15 pc from the Sun. Low-resolution spectral data from Magellan/FIRE and IRTF/SpeX reveal strong H2O and CO absorption features in the spectra of both components, with the secondary also exhibiting weak CH4 absorption at 1.6 micron and 2.2 micron. Spectral indices and comparison to low-resolution spectral standards indicate component types of L7.5 and T0.5, the former consistent with the optical classification of the primary. Relative photometry reveals a flux reversal between the J- and K-bands, with the T dwarf component being brighter in the 0.95--1.3 micron range. As with other L/T transition binaries, this reversal likely reflects significant depletion of condensate opacity across the transition, a behavior that may be enhanced in WISE J1049-5319AB if the unusual red color of its L dwarf component is indicative of thick clouds. On the other hand, differing cloud properties may have modified the evolutionary paths of these two components, and we propose a scenario in which the cooler secondary could be the more massive of the two components. Fortunately, the proximity, brightness and small separation (3.12+/-0.25 AU) of this system make it amenable to astrometric and radial velocity orbit measurement during its estimated 25 yr orbit, providing a rare opportunity for the direct determination of individual brown dwarf masses and a unique benchmark for studying cloud evolution across the L dwarf/T dwarf transition.
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