SPP 1573: Physics of the Interstellar Medium

星际空间充满了带电粒子、原子、分子和尘埃颗粒的稀薄混合物，称为星际介质(ISM)。ISM的平均粒子密度为1厘米-3，这意味着这个密度低于地球上可以创造的密度。因此，ISM代表着一个迷人的实验室，用于研究极端条件下的高度衰减气体的物理、化学过程以及原子、分子和固体物理以及许多其他自然科学问题。ISM的物理学在天文学的许多领域发挥着至关重要的作用。星系的形成和演化、恒星的形成、宇宙的核合成、大型复杂生物分子的起源和尘埃颗粒的丰富、结构和生长，这些构成了行星的基本组成部分，所有这些过程都与ISM的物理学密切相关。尽管它很重要，但它的结构和进化仍然鲜为人知。然而，情况正在迅速改善。用强大的望远镜进行的最新观测表明，ISM是一种湍流的多相气体，充满了所有可分辨空间尺度上的结构。这导致了我们对ISM的理解发生了范式转变，旧的平衡模型正被一幅高度动态的图景所取代，这些图景包含强耦合、相互作用和湍流混合的气相，这些气相远离平衡，并被不被很好理解的过程持续搅拌。这一发现引起了天文学界的极大兴趣。我们进入了一个时代，在这个时代，第一次有足够的信息可以获得对ISM及其演变的动力学过程的深入和全面的物理理解。这对天文学的许多领域都很重要。这一优先计划的主要目标是：(1)结合德国从事ISM物理不同方面工作的研究人员的专业知识，(2)从观测和理论上研究各种物理过程如何相互作用并塑造ISM，以及(3)构建动态、非线性、多相ISM的新模型。优先方案的最终目标是对多阶段国际空间物理管理有一个全面的物理理解，为天体物理学的其他领域奠定坚实的基础。为了实现这一雄心勃勃的科学目标，该方案依赖于三个相辅相成的支柱：(1)实验室研究将提供分子和离子反应的必要数据以及关于尘埃物理的跃迁频率和数据，这是描述ISM的物理和化学所必需的。(2)观测是约束理论模型和洞察ISM的结构及其对银河环境的依赖的关键。(3)理论和数值模拟将阐明物理过程及其联合作用对ISM结构和湍流驱动的重要性。

Interstellar space is filled with a dilute mixture of charged particles, atoms, molecules and dust grains, called the interstellar medium (ISM). The average particle density of the ISM is 1 cm-3, which represents a density lower than can be created on Earth. The ISM therefore represents a fascinating laboratory to study the physics of highly attenuated gases, chemical processes and atomic, molecular and solid state physics under extreme conditions and numerous other questions of natural sciences. The physics of the ISM plays a crucial role in many areas of astronomy. Galaxy formation and evolution, the formation of stars, cosmic nucleosynthesis, the origin of large complex, prebiotic molecules and the abundance, structure and growth of dust grains, which constitute the fundamental building blocks of planets, all these processes are intimately coupled to the physics of the ISM. Despite its importance, its structure and evolution is still poorly understood. The situation is, however, improving rapidly. New observations with powerful telescopes have revealed that the ISM is a turbulent, multiphase gas, filled with structures on all resolvable spatial scales. This has lead to a paradigm shift in our understanding of the ISM, where the old equilibrium model is being replaced by a highly dynamical picture of strongly coupled, interacting and turbulently mixed gas phases that are far from equilibrium and that are continuously stirred by processes that are not well understood. This insight has attracted enormous interest in the astronomical community. We enter an era where for the first time enough information is available to gain a deep and comprehensive physical understanding of the ISM and the dynamical processes that govern its evolution. This is of importance for many fields in astronomy. The main aims of this Priority Programme are: (1) to combine the expertise of researchers in Germany who work on different aspects of ISM physics, (2) to investigate observationally and theoretically how various physical processes interact with one another and shape the ISM, and (3) to construct a new model of the dynamical, non-linear, multiphase ISM. The final goal of the Priority Programme is to develop a comprehensive physical understanding of the multi-phase ISM that provides a solid basis for other fields of astrophysics. To reach this ambitious scientific goal, the programme relies on three complementary pillars: (1) Laboratory studies will provide the necessary data of molecular and ionic reactions as well as transition frequencies and data on dust physics, which is required for the physical and chemical description of the ISM. (2) Observations are the key to constrain theoretical models and give insight into the structure of the ISM and its dependence on galactic environment. (3) Theory and numerical simulations will shed light on physical processes and the importance of their combined effect on structuring the ISM and the driving of turbulence.