On the origins and composition of planetesimals through studies of circumstellar disks

在理解行星是如何组装和相互作用以及其他天体（如彗星和小行星）的过程中，一个基本的复杂问题是我们无法直接观察这些天体的形成和演化。现在，新的设备正在为所有行星形成的星周盘打开一扇新的窗口，为我们提供了探测系统如何演化的能力，并测试了关于我们太阳系起源的一些关键假设。这项研究计划将以关键的磁盘系统为目标，利用这些磁盘中的气体和固体的测量来告知我们对太阳系最早时期的理解。在太阳系内，对彗星和小行星进行关键化学示踪剂的测量，如氘（氢的一种变体，带有一个额外的中子）与氢的比率（D/H），以了解这些物体自形成以来如何在太阳系中移动。支撑这一模型的假设是，早期太阳盘的D/H比在太阳附近较低，而在更远的地方较高。利用最近发现的年轻系统，其中彗星和小行星的形成已经开始或完成，但气体盘仍然存在，我们将用ALMA望远镜测量许多盘系统的D/H比，以验证早期太阳系模型的这一方面，从而增强我们对行星和盘（彗星和小行星）如何进化和相互作用的理解。此外，利用双子座行星成像仪（GPI）和即将发射的詹姆斯·韦伯太空望远镜等其他设施，我们将测量圆盘内部区域气体的运动，并将它们与固体的位置进行比较，以解释系统如何通过碰撞和物质损失随着时间的推移而动态演变。利用这些数据，我们将对行星系统中大型（行星）和小型（小行星和彗星）天体的迁移施加限制。

A fundamental complication in understanding how planets are assembled and interact with each other and other bodies (like comets and asteroids) has been our inability to directly observe the formation and evolution of these bodies. New facilities are now opening a new window on circumstellar disks, the location where all planets form, providing us with an ability to probe how systems evolve and to test some key assumptions about our own solar system's origins. This research proposal will target key disk systems to utilize the measurements of gases and solids in those disks to inform our understanding of the solar system's earliest times. Within the solar system, measurements of key chemical tracers, such as the ratio of deuterium, a variant of hydrogen with an extra neutron, to hydrogen (D/H) are made toward comets and asteroids to understand how those objects have moved around in the Solar System since their formation. Underpinning this model is the assumption that the D/H ratio in the early solar disk was low near the sun and higher further away. Using recently identified young systems in which comets and asteroid formation has begun or is complete but the gas disk remains, we will measure with the ALMA telescope the D/H ratio for a number of disk systems to verify this aspect of the early Solar System model, thereby enhancing our understanding of how the planets and disk (comets and asteroids) have evolved and interacted with each other. In addition, using other facilities like the Gemini Planet Imager (GPI) and the soon to be launched James Webb Space Telescope, we will measure the motions of gas in the inner regions of disks and compare them to the locations of solids in order to explain how the systems evolve dynamically through collisions and loss of material over time. Using these data, we will place constraints on the migration of large (planets) and small (asteroids and comets) bodies within planetary systems. My goal with this proposal is to maximize Canada’s scientific output of ALMA (the Atacama Large Millimeter/submillimeter Array, the first billion dollar ground based telescope) and GPI disk science. The students funded by this proposal will augment the population of Canadian-based researchers who work in one of the key areas of in which ALMA and GPI are designed to excel: evolution of planetary systems within circumstellar disks.