FIRST KECK NULLING OBSERVATIONS OF A YOUNG STELLAR OBJECT: PROBING THE CIRCUMSTELLAR ENVIRONMENT OF THE HERBIG Ae STAR MWC 325
FIRST KECK NULLING OBSERVATIONS OF A YOUNG STELLAR OBJECT: PROBING THE CIRCUMSTELLAR ENVIRONMENT OF THE HERBIG Ae STAR MWC 325
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对年轻恒星物体的首次 KECK 零观测：探测 HERBIG Ae STAR MWC 325 的星周环境
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发表时间：
2011
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通讯作者：
W. Traub
中科院分区：
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作者：
S. Ragland;K. Ohnaka;L. Hillenbrand;S. Ridgway;M. Colavita;R. Akeson;W. Cotton;W. Danchi;M. Hrynevich;R. Millan;W. Traub
我们提出了第一个n波段零化加上K波段和l波段V 2观测年轻的恒星物体，MWC 325，用85米基线凯克干涉仪。Keck nuller是为研究与碎片盘相关的微弱尘埃特征而设计的，但它也有独特的能力来研究在年轻恒星物体周围发现的密度较大的盘的温度和密度分布。在K、L和N处对MWC 325的干涉观测在光谱范围内包含了5个因子，因此，特别是当光谱分散在每个波段时，能够表征行星形成的内盘区域的结构。用均匀圆盘或高斯圆盘等几何模型拟合我们的观测结果表明，在2-12 μm波长范围内，表观尺寸随波长单调增加，证实了基于辐射传输模型的广泛假设，现在在宽波长范围内进行了空间分辨测量，即圆盘随着温度梯度而扩展。L波段和N波段的有效粒径分别比K波段大1.4倍和2.2倍。现有的干涉测量和光谱能量分布可以用一个平盘或弱阴影近平盘模型再现，只有在盘的外部区域有轻微的耀斑，由具有代表性的“亚微米”（0.1 μm）和“微米”（2 μm）颗粒组成，硅和石墨的比例为50:50。这与之前在其他赫比格Ae/Be恒星中发现的圆盘形成鲜明对比，表明赫比格Ae/Be恒星之间的圆盘性质存在很大差异。
We present the first N-band nulling plus K- and L-band V 2 observations of a young stellar object, MWC 325, taken with the 85 m baseline Keck Interferometer. The Keck nuller was designed for the study of faint dust signatures associated with debris disks, but it also has a unique capability for studying the temperature and density distribution of denser disks found around young stellar objects. Interferometric observations of MWC 325 at K, L, and N encompass a factor of five in spectral range and thus, especially when spectrally dispersed within each band, enable characterization of the structure of the inner disk regions where planets form. Fitting our observations with geometric models such as a uniform disk or a Gaussian disk show that the apparent size increases monotonically with wavelength in the 2–12 μm wavelength region, confirming the widely held assumption based on radiative transfer models, now with spatially resolved measurements over a broad wavelength range, that disks are extended with a temperature gradient. The effective size is a factor of about 1.4 and 2.2 larger in the L band and N band, respectively, compared to that in the K band. The existing interferometric measurements and the spectral energy distribution can be reproduced by a flat disk or a weakly shadowed nearly flat disk model, with only slight flaring in the outer regions of the disk, consisting of representative “sub-micron” (0.1 μm) and “micron” (2 μm) grains of a 50:50 ratio of silicate and graphite. This is in marked contrast to the disks previously found in other Herbig Ae/Be stars, suggesting a wide variety in the disk properties among Herbig Ae/Be stars.