U.S.-Japan Cooperative Research: Structure and Evolution of Protogiant Planet Formation

该奖项将为加州大学圣克鲁兹分校利克天文台的Peter H Bodenheimer教授及其同事和日本国家天文台的Satoru Ikeuchi教授及其同事之间为期两年的原巨行星形成合作研究项目提供支持。太阳系的形成是天体物理学和行星科学中最重要的未解决问题之一。最近积累的关于年轻恒星周围原恒星盘的存在和演化的观测数据似乎表明，类似于导致太阳系形成的系统可能是丰富的，并且行星系统的形成可能是一个持续的过程，而不是很久以前的事件。这个项目的目的是对巨行星的形成进行理论研究，以帮助解释这些观测结果。巨行星被认为是由原始太阳星云中存在的小固体粒子的积累而形成的。在这个核心形成了几个地球质量之后，人们相信原行星能够通过引力从星云中捕获相对大量的气体，并且最终的形成阶段主要是气体吸积。在这个项目中，打算使用三维流体力学计算机代码来分析气体吸积的过程。通过这一分析，希望确定质量吸积率作为时间的函数，自旋角动量吸积率作为时间的函数，以及原行星轨道位置的变化作为时间的函数。参与这次合作的美国和日本研究人员都对太阳系起源的一般问题进行了深入的研究，并因其过去在该学科领域的研究而受到高度评价。这两个小组的研究技能是非常互补的。如果这项研究取得成功，它将使我们对巨行星的最终质量是如何确定的以及常规卫星系统是如何起源的有一些了解，并且应该为我们理解行星和太阳系形成过程提供非常有价值的理论组成部分。

This award will provide support for a two year cooperative research project on protogiant planet formation, between Professor Peter H Bodenheimer and colleagues at the Lick Observatory, University of California, Santa Cruz, and Professor Satoru Ikeuchi and colleagues from the National Astronomical Observatory, Japan. The formation of the solar system is one of the most important unsolved problems in astrophysics and planetary science. Recently accumulated observational data on the existence and evolution of protostellar disks around young stars seem to indicate that systems, similar to those that lead to the formation of the solar system, may be abundant, and that the formation of planetary systems may be an ongoing process instead of a long-ago event. The aim of this project is to is to undertake a theoretical investigation of the formation of giant planets to help interpret these observations. Giant planets are thought to have been initiated by the accumulation of small solid particles that existed in the primordial solar nebula. After the build up of this core to a few earth masses, it is believed that the protoplanet was able to gravitationally capture relatively large amounts of gas from the nebula, and that the final formation stages were dominated by gas accretion. It is intended during this project to analyze this process of gas accretion, using a three-dimensional hydrodynamic computer code. Through this analysis, it is hoped to determine the mass accretion rate as a function of time, the rate of accretion of spin angular momentum as a function of time, and the change in the location of the protoplanetary orbit as a function of time. Both the US and Japanese researchers involved in this collaboration have made intensive investigations into the general problem of the origin of the solar system and are highly regarded for their past research in the subject area. The research skills of the two groups are very complementary. If the research is successful it should give us some insight into how the final mass of giant planets was determined and how the regular satellite systems originated, and should provide a very valuable theoretical component to our understanding of the process of planet and solar system formation.