Formation and Evolution of Protostellar Disks in Young Star Clusters: Implications for the Origin of Binary Stars and Substellar Objects

理解原恒星盘的形成和演化是星星形成理论的关键组成部分。这种盘的性质决定了双星星星形成的概率。此外，它们还定义了亚恒星质量物体（所谓的褐矮星）或行星和行星系统形成的环境。因此，对原恒星盘演化的详细了解对于理解太阳系外行星的性质至关重要，并且对于理解我们太阳系的起源非常重要。从长远来看，它可能因此有助于推测我们星球上生命的起源和宇宙其他地方生命的可能性。这些都是对公众具有极大吸引力的基本问题，该项目的具体目标是通过数值模拟研究恒星和亚恒星物体在湍流星际气体云中的形成。我们将非常详细地跟踪初生星星团中原恒星及其相关盘的演化。由于大多数恒星都是在星团环境中形成的，相互作用可能会极大地改变原恒星盘的演化特性以及它们产生恒星和亚恒星物体的能力。我们将试图理解和预测观测到的双星/多星系统的频率、星星形成的总效率、由此产生的星星团的有界性、恒星和亚恒星质量谱以及在星盘中形成亚恒星质量物体的概率。特别是，我们将详细研究磁盘碎片的效率作为形成棕矮星和巨型气体行星的可能机制，并跟踪这些系统作为致密星系团的一部分的长期动力学演化。

Understanding the formation and evolution of protostellar disks is a key ingredient in star formation theory. The properties of such disks determine the probability of binary star formation. Furthermore, they define the environment where substellar-mass objects, the so called brown dwarfs, or planets and planetary systems build up. Detailed knowledge of protostellar disk evolution therefore is essential for understanding the properties of extrasolar planets, and bears great importance for understanding the origin of our own solar system. In the long run it may thus contribute to speculations about the origin of life on our planet and the possibility of life in ohter parts of the universe. These are fundamental questions with great appeal to the general public.The specific aim of this project is to study the formation of stars and substellar objects in turbulent interstellar gas clouds by means of numerical simulations. We will follow in great detail the evolution of protostars and their associated disks in nascent star clusters. As most stars form in a clustered environment, mutual interactions may drastically alter the evolutionary properties of protostellar disks and their ability to give birth to stars and substellar objects. This link has not yet been studied in sufficient detail and with sufficient numerical resolution.We will try to understand and predict the observed frequency of binary/multiple stellar systems, the overall efficiency of star formation, the boundedness of the resulting star clusters, the stellar and substellar mass spectrum, and the probability of forming substellar-mass objects in the disk. In particular, we will investigate in detail the efficiency of disk fragmentation as a possible mechanism for forming brown dwarfs and giant gas planets, and follow the long-term dynamical evolution of such systems as parts of dense clusters.