The complex structure of the disk around HD 100546 - The inner few astronomical units
The complex structure of the disk around HD 100546 - The inner few astronomical units
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HD 100546周围圆盘的复杂结构 - 内部的几个天文单位
DOI：
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发表时间：
2010
期刊：
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通讯作者：
Mark R. Swain
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文献类型：
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作者：
M. Benisty;E. Tatulli;F. Menard;Mark R. Swain
揭示围绕赫比格AeBe恒星的圆盘结构对于扩大我们对恒星和行星形成和早期演化的理解非常重要。我们的目标是揭示10 Myr老赫比格Be星HD100546周围的亚天文单位的盘状结构，并研究其近红外和中红外过剩的起源。我们使用AMBER/VLTI观测来解析k波段发射，并确定了最内层盘中热尘埃的位置和组成。结合琥珀观测与文献中的光度测量和MIDI/VLTI测量，我们使用基于三维辐射传输的被动磁盘模型重新审视磁盘的几何形状。我们提出了一个模型，其中包括一个由微米大小的尘埃颗粒组成的薄内盘，一个间隙和一个巨大的光学厚外盘，成功地再现了干涉测量数据和SED。我们将k波段发射的大部分定位在~0.26 AU。假设这种发射来自硅酸盐，我们表明，微米大小的颗粒是使尘埃能够在离恒星这么远的地方存活下来的必要条件。因此，超过40%的k波段通量与散射有关，表明直接热发射不足以解释近红外过剩。在巨大的外盘中，中间面的大颗粒负责毫米发射，而表面的小颗粒层允许再现中远红外过量。这种垂直构造可能是沉积的证据。观测结果与一个模型一致，该模型包括一个直到~13天文单位的间隙，其内部的总尘埃质量为~0.008个月球质量。这些数值与导出的尺度高度（~2.5 AU）和外盘内缘温度（~220 K） （r=13 AU）与最近的CO观测结果一致。
Disclosing the structure of disks surrounding Herbig AeBe stars is important to expand our understanding of the formation and early evolution of stars and planets. We aim at revealing the sub-AU disk structure around the 10 Myr old Herbig Be star HD100546 and at investigating the origin of its near and mid-infrared excess. We used AMBER/VLTI observations to resolve the K-band emission and to constrain the location and composition of the hot dust in the innermost disk. Combining AMBER observations with photometric and MIDI/VLTI measurements from the litterature, we revisit the disk geometry using a passive disk model based on 3D radiative transfer. We propose a model that includes a tenuous inner disk made of micron-sized dust grains, a gap, and a massive optically thick outer disk, that successfully reproduces the interferometric data and the SED. We locate the bulk of the K-band emission at ~0.26 AU. Assuming that this emission originates from silicate, we show that micron-sized grains are required to enable the dust to survive at such a distance from the star. As a consequence, more than 40% of the K-band flux is related to scattering, showing that direct thermal emission is not sufficient to explain the near-infrared excess. In the massive outer disk, large grains in the mid-plane are responsible for the mm emission while a surface layer of small grains allows the mid and far infrared excesses to be reproduced. Such vertical structure may be an evidence for sedimentation. The observations are consistent with a model that includes a gap until ~13 AU and a total dust mass of ~0.008 lunar mass inside it. These values together with the derived scale height (~2.5 AU) and temperature (~220 K) at the inner edge of the outer disk (r=13 AU), are consistent with recent CO observations.