论文标题
膨胀后的信封棕色矮人NLTT 5306b的近红外光谱
Near-infrared spectra of the inflated post-common envelope brown dwarf NLTT 5306B
论文作者
论文摘要
NLTT 5306是由白色矮人宿主和棕色矮人伴侣组成的常见后包膜二元，尽管没有填充其Roche Lobe，但仍显示出通货膨胀和主动批量捐赠的证据。棕色矮人通货膨胀的两种提出的机制是磁相互作用和高金属性，云彩气氛。我们提出中等分辨率（$ r \ lyssim2000 $）$ J $ band Keck/nirspec对此系统的观察。这些相分辨的数据使我们能够限制棕色矮人白天和夜间大气参数之间的差异。与Casewell等人的亮度温度测量值一致，我们的白天和夜间有效温度测量是一致的。 2021a。日间有利于稍低的表面重力，也许是由于两个物体之间的材料流。最后，我们的数据显示了对低金属性模型的偏爱。这是从系统的老年中预期的，但可以直接证据表明高金属性，多云的棕色矮人气氛对见证的通货膨胀概不负责。这些结果加强了导致NLTT 5306 B膨胀的磁相互作用的情况。
NLTT 5306 is a post-common envelope binary made up of a white dwarf host and brown dwarf companion that has shown evidence of inflation and active mass donation despite not filling its Roche lobe. Two proposed mechanisms for the brown dwarf's inflation are magnetic interactions and a high metallicity, cloudy atmosphere. We present moderate resolution ($R\lesssim2000$) $J$ band Keck/NIRSPEC observations of this system. These phase-resolved data allow us to constrain differences between atmospheric parameters of the day- and night-side of the brown dwarf. Our day- and night-side effective temperature measurements are consistent, in agreement with the brightness temperatures measurements from Casewell et al. 2021a. The day-side favors a slightly lower surface gravity, perhaps stemming from the material streaming between the two objects. Finally, our data show a preference for low metallicity models. This would be expected from the system's old age, but provides direct evidence that a high metallicity, cloudy brown dwarf atmosphere is not responsible for the witnessed inflation. These results strengthen the case for magnetic interactions leading to inflation of NLTT 5306 B.
