论文标题
TW Hya Rosetta Stone项目III：解决磁盘的气体热轮廓
The TW Hya Rosetta Stone Project III: Resolving the Gaseous Thermal Profile of the Disk
论文作者
论文摘要
原星盘的热结构是系统的基本特征，对磁盘的演化和行星形成具有广泛的影响。在这项研究中，我们利用七个CO线的图像来限制原星盘TW HYA结构的2D热结构。这包括12CO J = 2-1和C18O J = 2-1的新的ALMA观察结果，以及12CO J = 3-2、13CO j = 3-2、6-5、6-5，C18O J = 3-2、6-5的档案ALMA观测值。此外，我们重现了HD j = 1-0线通量的Herschel观察，光谱能量分布，并利用了TW HYA中CO径向耗竭的近期定量。这些观察结果是使用热化学代码RAC2D建模的，我们的最佳拟合模型再现了所有空间分辨的CO表面亮度曲线。所得的热轮廓发现磁盘质量为0.025 msun，薄薄的气体上层耗尽了小灰尘，厚度约为相应半径的1.2％。使用我们的最终热结构，我们发现单独的CO不是一个可行的质量示踪剂，因为它的丰度随着H2表面密度而变质。不同的质量模型可以很容易地与空间解析的CO线轮廓匹配不同的丰度假设。质量确定需要额外的知识，在这项工作中，HD提供了额外的约束，以得出气体质量并支持TW HYA磁盘中CO耗竭的推断。我们的最终热结构证实了HD用作原动性磁盘质量的强大探针。此外，本文提出的方法是提取磁盘温度和质量的可用策略。
The thermal structure of protoplanetary disks is a fundamental characteristic of the system that has wide reaching effects on disk evolution and planet formation. In this study, we constrain the 2D thermal structure of the protoplanetary disk TW Hya structure utilizing images of seven CO lines. This includes new ALMA observations of 12CO J=2-1 and C18O J=2-1 as well as archival ALMA observations of 12CO J=3-2, 13CO J=3-2, 6-5, C18O J= 3-2, 6-5. Additionally, we reproduce a Herschel observation of the HD J=1-0 line flux, the spectral energy distribution, and utilize a recent quantification of CO radial depletion in TW Hya. These observations were modeled using the thermochemical code RAC2D, and our best fit model reproduces all spatially resolved CO surface brightness profiles. The resulting thermal profile finds a disk mass of 0.025 Msun and a thin upper layer of gas depleted of small dust with a thickness of approx 1.2% of the corresponding radius. Using our final thermal structure, we find that CO alone is not a viable mass tracer as its abundance is degenerate with the total H2 surface density. Different mass models can readily match the spatially resolved CO line profiles with disparate abundance assumptions. Mass determination requires additional knowledge and, in this work, HD provides the additional constraint to derive the gas mass and supports the inference of CO depletion in the TW Hya disk. Our final thermal structure confirms the use of HD as a powerful probe of protoplanetary disk mass. Additionally, the method laid out in this paper is an employable strategy for extraction of disk temperatures and masses in the future.
