Giant Planet Core Formation

木星和土星对行星形成理论提出了挑战。作为气态巨行星，它们必须在不到1000万年的时间内形成，才能在太阳星云消散之前吸积气体。目前关于巨行星形成的主要理论是核心吸积模型，在该模型中，一个大型行星胚胎首先通过固体星子的吸积形成，随后当它增长到大约10个地球质量时吸积气体。然而，这个模型有一个弱点，即大胚胎的初始增生受到各种物理过程的阻碍。在这个更新的项目中，首席研究员，博士后研究员和合作者将继续开发一个广泛的核心吸积的计算机模型，以确定这个理论是否可行。该团队将对嵌入太阳星云中的胚胎和星子系统的进化进行一系列模拟。这些模型将包括：(i)星子和胚胎的直接引力相互作用，（ii）星子的空气动力阻力，（iii）胚胎通过与原行星盘的引力相互作用而迁移，（iv）胚胎破碎，(v)胚胎大气的影响，（vi）雪线处固体的积累，以及（vii）湍流驱动的胚胎迁移。该团队的n体代码将与最先进的太阳星云模型相结合，以确定（ii）， （iii）和（vi）如何随时间变化。这个项目与太阳系的历史广泛相关，对地球也有影响。水的获取。该项目将支持一位女科学家的早期职业发展。首席研究员将继续参与公共宣传、广播和印刷媒体。

Jupiter and Saturn represent a challenge to theories of planet formation. Being gas giants, they must have formed in less than 10 million years to be able to accrete gas from the solar nebula before it dissipated. The current leading theory for giant planet formation is the core accretion model, in which a large planetary embryo forms first by accretion of solid planetesimals, and subsequently accretes gas when it has grown to approximately 10 Earth masses. However, this model has a weakness, in that the initial accretion of a large embryo is hindered by a variety of physical processes. In this renewed project, the Principal Investigator, a postdoctoral researcher, and collaborators will continue to develop an extensive computer model of core accretion in order to determine whether this theory is viable. The team will perform a series of simulations of the evolution of a system of embryos and planetesimals embedded in the solar nebula. The models will include: (i) direct gravitational interaction of the planetesimals and embryos, (ii) aerodynamic drag on the planetesimals, (iii) migration of the embryos through gravitational interaction with the protoplanetary disk, (iv) embryo fragmentation, (v) the effects of embryos' atmospheres, (vi) the buildup of solids at the snow-line, and (vii) turbulence-driven migration of the embryos. The team's N-body code will be coupled with state-of-the-art models of the solar nebula in order to determine how (ii), (iii) and (vi) change with time. The project is broadly relevant to the history of the Solar System and has implications for Earth?s acquisition of water. The project will support the early career development of a woman scientist. The Principal Investigator will continue his involvement with public outreach and broadcast and print media.