Formation and dynamical evolution of planetary systems

点击翻译按钮获取中文摘要

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.