arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1303.6499astro-ph.SRastro-ph.EP
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蝴蝶星拱盘中大尘埃颗粒的垂直沉降和径向分离

Vertical settling and radial segregation of large dust grains in the circumstellar disk of the Butterfly Star

Christian Gräfe, Sebastian Wolf, Stephane Guilloteau, Anne Dutrey, Karl Stapelfeldt, Klaus Pontoppidan, Jürgen Sauter

摘要:

背景:星周盘被认为是行星形成的环境。尘埃颗粒在这些圆盘中的生长是核心吸积气体捕获行星形成场景的第一步。可以在空间分辨图像和这些物体的光谱能量分布中追踪盘演化的指标和证据。目的:我们开发了一个模型的尘埃阶段的边缘上定向拱星盘的蝴蝶星,它允许一个适合观察到的多波长图像和SED同时。研究方法:我们的模型是基于空间分辨的高角分辨率的意见,在1.3毫米,894微米,2.07微米,1.87微米,1.60微米,1.13微米和广泛覆盖的SED范围从12微米到2.7毫米,包括详细的光谱与斯皮策太空望远镜获得的范围从12微米到38微米。基于网格搜索方法的参数研究,包括对每个参数的详细分析,以约束圆盘参数并找到独立观测的最佳拟合模型。使用我们的连续辐射转移代码,同时对单个观测进行建模。结果:我们得到了一个模型,能够在同一时间再现所有的磁盘的意见。我们发现定量的证据,晶粒生长到~100微米大小的颗粒,垂直沉降的较大的尘埃颗粒向磁盘中平面,和径向偏析的后者向中央恒星。在我们的最佳拟合模型中,大颗粒的分布在100 AU处的尺度高度为3.7 AU,径向范围为175 AU,而在100 AU处的流体静力学尺度高度为6.9 AU,外盘半径为300 AU。我们的研究结果与目前的拱星盘演化和行星形成早期阶段的理论模型是一致的。

英文摘要:

Context: Circumstellar disks are considered to be the environment for the formation of planets. The growth of dust grains in these disks is the first step in the core accretion-gas capture planet formation scenario. Indicators and evidence of disk evolution can be traced in spatially resolved images and the spectral energy distribution (SED) of these objects. Aims: We develop a model for the dust phase of the edge-on oriented circumstellar disk of the Butterfly Star which allows one to fit observed multi-wavelength images and the SED simultaneously. Methods: Our model is based on spatially resolved high angular resolution observations at 1.3 mm, 894 micron, 2.07 micron, 1.87 micron, 1.60 micron, and 1.13 micron and an extensively covered SED ranging from 12 micron to 2.7 mm, including a detailed spectrum obtained with the Spitzer Space Telescope in the range from 12 micron to 38 micron. A parameter study based on a grid search method involving the detailed analysis of every parameter was performed to constrain the disk parameters and find the best-fit model for the independent observations. The individual observations were modeled simultaneously, using our continuum radiative transfer code. Results: We derived a model that is capable of reproducing all of the observations of the disk at the same time. We find quantitative evidence for grain growth up to ~100 micron-sized particles, vertical settling of larger dust grains toward the disk midplane, and radial segregation of the latter toward the central star. Within our best-fit model the large grains have a distribution with a scale height of 3.7 AU at 100 AU and a radial extent of 175 AU compared to a hydrostatic scale height of 6.9 AU at 100 AU and an outer disk radius of 300 AU. Our results are consistent with current theoretical models for the evolution of circumstellar disks and the early stages of planet formation.

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