标题： TW Hya周围盘的0.5-2.22微米散射光谱：在80天文单位处部分填充的盘间隙的探测 显示英文标题

标题： The 0.5-2.22-micron Scattered Light Spectrum of the Disk Around TW Hya: Detection of a Partially Filled Disk Gap at 80 AU

摘要： 我们通过结合空间分辨的哈勃太空望远镜（HST）空间巡天与广域相机（STIS）光谱以及盘面的日冕成像仪（NICMOS）图像，得到了TW Hya周围恒星盘0.5-2.2微米的散射光谱。 我们在这一宽波长范围内研究了距离>40天文单位处盘面的形态，并识别出约80天文单位处亮度下降的现象，这可能是盘面存在间隙所导致的。 此外，我们量化了盘面的表面亮度、方位对称性以及光谱特征随半径的变化。 我们的分析表明，尘埃的散射效率在观测波长范围内大致呈中性至蓝色。 我们将盘面建模为具有人为设定间隙结构的稳定α盘。 盘面的热性质使用三维辐射传递代码自洽地计算，该代码使用光线追踪来模拟盘面内部的加热和散射光图像。 如果我们使用一个模型盘，在80天文单位处有一个深度为30%的部分填充间隙，并在100天文单位处具有自相似截断膝部，那么我们发现这个模型在整个距离范围上都能很好地拟合数据。 间隙的起源尚不清楚，但它可能源于盘面尘埃成分性质的转变或行星伴星的存在。 基于嵌入式原行星开启间隙标准的先前流体力学模拟尺度估计，我们认为形成间隙的行星伴星的质量可能在6到28个地球质量之间。 显示英文摘要

摘要： We present a 0.5-2.2 micron scattered light spectrum of the circumstellar disk around TW Hya from a combination of spatially resolved HST STIS spectroscopy and NICMOS coronagraphic images of the disk. We investigate the morphology of the disk at distances > 40 AU over this wide range of wavelengths, and identify the presence of a depression in surface brightness at ~80 AU that could be caused by a gap in the disk. Additionally, we quantify the surface brightness, azimuthal symmetry, and spectral character of the disk as a function of radius. Our analysis shows that the scattering efficiency of the dust is largely neutral to blue over the observed wavelengths. We model the disk as a steady alpha-disk with an ad hoc gap structure. The thermal properties of the disk are self-consistently calculated using a three-dimensional radiative transfer code that uses ray-tracing to model the heating of the disk interior and scattered light images. We find a good fit to the data over a wide range of distances from the star if we use a model disk with a partially filled gap of 30% depth at 80 AU and with a self-similar truncation knee at 100 AU. The origin of the gap is unclear, but it could arise from a transition in the nature of the disk's dust composition or the presence of a planetary companion. Based on scalings to previous hydrodynamic simulations of gap opening criteria for embedded proto-planets, we estimate that a planetary companion forming the gap could have a mass between 6-28 M_Earth.