Formation and dynamical evolution of planetary systems

我们的太阳系有多典型？行星系统如何形成和动态演化的问题是天文学中最古老的未解决问题之一。在过去的十年中，已经发现了显着的观测线索，包括i）海王星以外巨大水库中的数千个冰体，ii）新形成的恒星周围的许多行星形成的气体和尘埃盘，iii）许多附近成熟恒星周围的数百个不寻常的行星系统。 这些发现挑战了行星形成的“标准模型”的许多方面，例如，需要在海王星以外的彗星区域创造复杂的扰动结构的机制，不仅影响轨道的偏心率（“形状”），而且诱导我们自己系统和其他恒星周围的行星向内或向外螺旋。 然而，人们仍然普遍认为，大多数行星的核心是由类似于彗星和小行星的小得多的天体堆积而成的。 由于其动力学的混沌性质，理解这类系统的形成和动力学演化的最有力的理论方法是构建计算机模型，以数值方式跟踪数百万至数十亿年的大量引力相互作用物体的轨道，包括与气体盘的相互作用和/或物体之间的物理碰撞的影响。 我和我的学生及合作者研究的许多问题都使用了一个非常有效的计算机软件包，称为SWIFT，最初由H。Levison（西南研究所）和我，并在国际上广泛使用。 我们正在整合各种方法，以更有效地模拟不断增长的行星与较小天体的相互作用，现在正准备解决迄今为止在计算上难以解决的紧迫问题。 其中包括对巨行星形成的广泛模拟，以及对行星形成过程和太阳形成的恒星孕育区对海王星以外彗星储集层的影响的模拟。

How typical is our Solar System? The issue of how planetary systems form and dynamically evolve is one of the oldest unsolved problems in astronomy. In the past decade, remarkable observational clues have been found including i) thousands of icy bodies in vast reservoirs beyond Neptune, ii) numerous planet-forming disks of gas and dust around newly forming stars and iii) hundreds of unusual planetary systems around many nearby mature stars. These discoveries challenge many aspects of what had become the "standard model" of planet formation, requiring, for example, mechanisms to create the intricately disturbed structure in the cometary region beyond Neptune and to affect not only the eccentricities ("shapes") of orbits but to induce spiralling inward or outward of planets in our own system and those around other stars. It is still widely believed, however, that the cores of most planets are formed from the accumulation of much smaller bodies similar to comets and asteroids. Due to the generally chaotic nature of their dynamics, the most powerful theoretical method for understanding the formation and dynamical evolution of such systems is to construct computer models to numerically follow the orbits of large numbers of gravitationally interacting bodies for millions to billions of years, including the effects of interactions with the gas disk and/or physical collisions among the bodies. Many of the problems I am studying with my students and collaborators utilize a very efficient computer software package called SWIFT, originally developed by H. Levison (SouthWest Research Institute) and me, and widely used internationally. We are incorporating a variety of methods to more efficiently model the interaction of growing planets with a population of smaller bodies and are now poised to tackle pressing problems that have been hitherto computationally intractable. These include extensive simulations of the formation of giant planets and simulations of the influence on the cometary reservoirs beyond Neptune of the planet-building process and the stellar nursery in which the Sun formed.