标题： 斯皮策望远镜对双褐矮星2MASS J04414489+2301513的中心天体周围的盘状结构的光谱观测 显示英文标题

标题： Spitzer Spectroscopy of the Circumprimary Disk in the Binary Brown Dwarf 2MASS J04414489+2301513

摘要： 利用斯皮策红外光谱仪，我们对金牛座恒星形成区中的年轻双星褐矮星 2MASS J04414489+2301513（15 AU）进行了中红外光谱观测。 光谱显示出过量的连续辐射发射，这可能来自主星周围的原恒星盘。 这些数据中未检测到硅酸盐发射，表明存在显著的颗粒生长。 这是少数已知的如此年轻年龄（~1 百万年）的褐矮星盘之一，其缺乏硅酸盐发射。 为了定量限制盘的性质，我们将 2MASS J04414489+2301513 的光谱能量分布与我们针对受照吸积盘的垂直结构代码预测的结果进行了比较。 我们的模型表明，中度贫化层的剩余大气颗粒可能已经长大到 $\gtrsim5$微米的尺寸。 此外，我们的模型拟合显示盘的外半径为 0.2-0.3 AU。 这个环绕主星的盘的小尺寸可能是由次级星截断引起的。 外盘中缺乏含有小原始颗粒的储库，加上较弱的湍流机制，可能是导致该盘中颗粒生长先进的原因。 显示英文摘要

摘要： Using the Spitzer Infrared Spectrograph, we have performed mid-infrared spectroscopy on the young binary brown dwarf 2MASS J04414489+2301513 (15 AU) in the Taurus star-forming region. The spectrum exhibits excess continuum emission that likely arises from a circumstellar disk around the primary. Silicate emission is not detected in these data, indicating the presence of significant grain growth. This is one of the few brown dwarf disks at such a young age (~1 Myr) that has been found to lack silicate emission. To quantitatively constrain the properties of the disk, we have compared the spectral energy distribution of 2MASS J04414489+2301513 to the predictions of our vertical structure codes for irradiated accretion disks. Our models suggest that the remaining atmospheric grains of moderately depleted layers may have grown to a size of $\gtrsim5$ micron. In addition, our model fits indicate an outer radius of 0.2-0.3 AU for the disk. The small size of this circumprimary disk could be due to truncation by the secondary. The absence of an outer disk containing a reservoir of small, primordial grains, combined with a weak turbulent mechanism, may be responsible for the advanced grain growth in this disk.