早期行星形成于嵌入式盘（eDisk）. XXV. 倾角引起的短轴亮度不对称性揭示嵌入式原恒星盘中有限的尘埃沉降
Early Planet Formation in Embedded Disks (eDisk). XXV. Inclination-Induced Minor-Axis Brightness Asymmetries Reveal Limited Dust Settling in Embedded Protostellar Disks
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中文总结 AI 辅助
本研究利用高倾角盘的短轴亮度不对称性作为几何诊断，通过辐射传输建模和MCMC拟合分析eDisk样本，发现嵌入式原恒星盘尘埃沉降有限，沉降主要发生在Class I阶段，且与亚结构形成时间重合。
中文摘要 AI 辅助
尘埃在年轻原恒星盘中如何以及何时沉降，是理解行星esimal乃至最终行星形成所需尘埃浓度的关键开放问题。然而，直接测量嵌入式（Class 0/I）系统中的垂直尘埃分布仍具挑战性。我们表明，高倾角盘沿短轴的亮度不对称性提供了垂直尘埃结构的简单而有力的几何诊断。利用RADMC-3D辐射传输模型，我们生成合成连续谱图像，显示所观测的不对称性自然源于盘倾角、光学深度和尘埃标高。我们将此框架应用于ALMA大型项目“早期行星形成于嵌入式盘（eDisk）”中的九个Class 0和I盘，采用马尔可夫链蒙特卡洛（MCMC）拟合。外向流观测独立验证了推断的近侧和远侧几何结构：所有八个具有有用外向流约束的源均与尘埃连续谱建模预测的取向一致。我们的结果表明，大多数嵌入式盘未显示显著尘埃沉降的强证据，尘埃标高与气体标高相当。鉴于文献表明Class II盘倾向于良好沉降，我们的结果强化了以下观点：显著尘埃沉降发生在Class I阶段，即深度嵌入的Class 0盘过渡到更显露的Class II对应体时。有趣的是，尘埃沉降的时间似乎与广泛尘埃亚结构的形成大致重合，暗示引力驱动的垂直尘埃浓缩可能触发了亚结构形成。
英文摘要
How and when dust settles in young protostellar disks is a key open question for the dust concentration needed to form planetesimals and, ultimately, planets. However, directly measuring the vertical dust distribution in embedded (Class 0/I) systems remains challenging. We show that brightness asymmetry along the minor axis of highly inclined disks provides a simple, powerful geometric diagnostic of vertical dust structure. Using radiative transfer modeling with RADMC-3D, we generate synthetic continuum images showing that the observed asymmetry arises naturally from disk inclination, optical depth, and dust scale height. We apply this framework to nine Class 0 and I disks from the ALMA Large Program, Early Planet Formation in Embedded Disks (eDisk), using Markov Chain Monte Carlo (MCMC) fitting. Outflow observations independently validate the inferred near- and far-side geometries: all eight sources with useful outflow constraints agree with the orientations predicted by the dust continuum modeling. Our results indicate that most embedded disks show no strong evidence of significant dust settling, with dust scale heights comparable to the gas scale height. Given that the literature indicates Class II disks tend to be well settled, our results reinforce the notion that significant dust settling occurs during the Class I phase, when deeply embedded Class 0 disks transition to their more revealed Class II counterparts. Intriguingly, the timing of dust settling appears to broadly coincide with the development of widespread dust substructures, suggesting that gravitationally driven vertical dust concentration may have triggered substructure formation.
发表机构
- University of Virginia（弗吉尼亚大学）
- Virginia Institute of Theoretical Astronomy, University of Virginia（弗吉尼亚大学理论天文研究所）
- National Radio Astronomy Observatory（国家射电天文台）
- Kagoshima University（鹿儿岛大学）
机构由 AI 辅助整理，请以论文原文为准。
