Planet Formation in Turbulent Disks

湍流盘中的行星形成

• 批准号: 0807471
• 负责人: Philip Armitage
• 金额: $ 45.55万
• 依托单位: University of Colorado at Boulder
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-09-01 至 2012-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0807471&HistoricalAwards=false
• 关键词: Planet; Formation; Turbulent; Disks

The focus of this project is the study the mechanisms responsible for driving turbulence in protoplanetary disks, and the effect of such turbulence on two critical stages of the planet formation process - the motion of dust within the disk and the early growth of kilometer-scale bodies called planetesimals. Here, Dr. Armitage and a postdoctoral scholar will develop new global simulations of protoplanetary disks that will be used to study two important sources of turbulence: that driven by the magnetorotational instability and that generated by the self-gravity of the disk gas. The simulations will improve upon prior work both by attaining higher resolution, and by more accurately reproducing the physical conditions likely to exist in young protoplanetary disks. Using the simulations, they will determine how efficiently dust diffuses within the turbulence, and in particular whether the large-scale structure of the turbulent disk enhances the transport as compared to local models. They will also calculate the equilibrium velocity dispersion of bodies within the disk, whose orbits are excited by gravitational scattering off turbulent fluctuations and damped by gas drag. From this, they will determine the prerequisites for planetesimals to grow rather than suffer destructive collisions. The results are expected to elucidate where in the disk planet formation can occur, and whether significant steps toward growth can occur in the earliest phases of disk evolution when the disk is massive and turbulent. This project will directly contribute to the professional training of a junior scientist. Also, during the grant period, Dr. Armitage will complete and publish a graduate level textbook entitled "Astrophysics of Planet Formation," which will cover topics directly relevant to this project and which will incorporate results of this research. At the undergraduate level, Dr. Armitage will integrate selected aspects of this work into a class for non-science majors on "Extraterrestrial Life," make course materials available electronically, and continue his participation in NSF-supported experiments into new techniques for teaching science. For the general public, he will revise an existing planetarium show on extra-solar planets, both to incorporate new results and to take advantage of improved digital technology at the University of Colorado's Fiske Planetarium. The technical results of the investigation will be disseminated widely via journal articles that are freely via the arXiv preprint server.

该项目的重点是研究原行星盘中驱动湍流的机制，以及这种湍流对行星形成过程的两个关键阶段--行星盘内尘埃的运动和被称为行星体的千米级天体的早期生长的影响。在这里，阿米蒂奇博士和一名博士后学者将对原行星盘进行新的全球模拟，用来研究两个重要的湍流来源：一个是由磁致旋转不稳定性驱动的湍流，另一个是由盘状气体的自引力产生的湍流。通过获得更高的分辨率，并通过更准确地再现年轻的原行星盘中可能存在的物理条件，模拟将在先前工作的基础上得到改进。利用模拟，他们将确定尘埃在湍流中扩散的效率，特别是与局部模型相比，湍流盘的大尺度结构是否增强了输送。他们还将计算圆盘内物体的平衡速度色散，这些物体的轨道是由湍流涨落引起的引力散射激发的，并受到气体阻力的抑制。由此，他们将确定小行星生长的先决条件，而不是遭受破坏性的碰撞。这些结果有望阐明在磁盘行星形成的什么地方可以发生，以及当磁盘质量大和动荡时，在磁盘演化的早期阶段是否会出现朝着增长的重要步骤。该项目将直接为初级科学家的专业培训做出贡献。此外，在授予期间，阿米蒂奇博士将完成并出版一本名为《行星形成的天体物理学》的研究生水平教科书，其中将涵盖与这一项目直接相关的主题，并将纳入这项研究的成果。在本科生阶段，阿米蒂奇博士将把这项工作的某些方面整合到一个面向非理科专业学生的“外星生命”课程中，以电子方式提供课程材料，并继续参与国家科学基金会资助的实验，将其转化为教授科学的新技术。对于普通公众，他将修改现有的太阳系外行星天文馆展览，既纳入新的结果，又利用科罗拉多大学菲斯克天文馆改进的数字技术。调查的技术结果将通过期刊文章广泛传播，这些文章可通过arxiv预印服务器免费获得。