Planetesimals, Planets, and Debris

我建议进行行星天体物理学的研究，这将有助于我们了解太阳系是如何形成和演变的。这项研究将首先关注行星（微行星）的构建模块如何发展，其次关注由此产生的系统如何随时间演变。这项研究的自然选择是剑桥大学应用数学和理论物理系，那里的天体物理组有一个新的重点是行星形成，磁盘动力学和行星环由约翰·帕帕洛伊佐教授和戈登·奥格尔维博士领导。这项研究特别及时，因为探测行星和原行星系统的观测能力在过去几年中显著增长，并开始为行星形成模型提供严格的限制。与此同时，计算机集群已经变得快速，合理便宜，易于管理，可以处理有趣的大问题。最后，理论模型已经发展到可以通过数值模拟进行详细测试，并将结果直接与观测结果进行比较的地步。拟议的工作将包括直接的数值模拟，目标是描述星子的形成方式，并对决定星周盘最终状态的参数进行定量约束。我将开始通过一系列的直接数值模拟测试模型的星子形成。这些模拟将解决并可能解决行星形成过程中尘埃增长的长期问题。小行星的形成很难通过观测来研究，因为这些物体太大，无法在尘埃盘调查中检测到，又太小，无法通过自己的发射来检测。此外，数值模型和计算技术还不足以直接解决这个问题。我提供了一种方法，利用一个有效的和通用的数字代码，允许创建的灰尘聚集。然后可以将结果与年轻恒星周围尘埃盘的观测结果进行比较。此外，我建议研究行星系统如何形成，以及为什么一些成熟的恒星似乎有碎片盘。我在这里提出的盘演化工作将能够确定在成熟恒星周围观察到的碎片盘是否是柯伊伯带状物体（这有助于我们太阳系中的尘埃）的研磨结果或演化的不同阶段。我建议在剑桥大学DAMTP的天体物理组进行这项工作，因为他们在行星形成和盘动力学研究方面具有相当的专业知识。

I propose to conduct research in planetary astrophysics that will contribute to our understanding of how solar systems formed and evolved. This research will first focus on how the building blocks of planets (planetesimals) develop and second on how the resulting system evolves over time. The natural choice of institution for this research is the Department of Applied Mathematics and Theoretical Physics, University of Cambridge, where the Astrophysics Group has a new emphasis on planet formation, disk dynamics, and planetary rings led by Prof. John Papaloizou and Dr. Gordon Ogilvie. The research is particularly timely because observational capabilities to detect both planetary and protoplanetary systems have grown significantly in the past few years, and are beginning to provide stringent constraints for models of planet formation. At the same time computer clusters have become fast, reasonably cheap, and easy to manage and can handle interestingly large problems. Finally, theoretical models have advanced to the point were they can be tested in detail with numerical simulations and the results directly compared to observations. The proposed work will consist of direct numerical simulations with a goal to characterize how planetesimals form and to put quantitative constraints on the parameters that determine the final state of the circumstellar disks. I will begin by testing models of planetesimal formation through a series of direct numerical simulations. These simulations will address and potentially solve the long-standing problem of dust growth in planet formation. Planetesimal formation is difficult to study observationally because the objects are too large to detect in dust disk surveys and too small to be detected through their own emission. In addition, numerical models and computational techniques have simply not been powerful enough to address the problem directly. I provide a method that utilizes an efficient and versatile numerical code that allows the creation of dust aggregates. The results can then be compared with observations of dusty disks around young stars. In addition, I propose to study how planetary systems form and why some mature stars seem to have disks of debris. The disk evolution work that I propose here will be able to determine if the debris disks that are observed around mature stars are the result of the grinding of Kuiper Belt-like objects (which contribute to the dust in our solar system) or a different phase of evolution. I propose to conduct this work in the Astrophysics Group at DAMTP, Cambridge University because of their considerable expertise in the study of planet formation and disk dynamics.