Star Formation out of the Magnetised Interstellar Medium

磁场是星际介质(ISM)的基本组成部分，对星际介质在不同空间尺度上的动力学有很大影响。一个长期存在的问题是它们对星系中恒星形成的影响。与热压类似，如果磁场足够强，磁场可以防止自引力气团收缩。因此，气体的超密度必须是磁性超临界的，用质量流量比来量化，才能崩塌并随后允许恒星的形成。越来越多的证据表明，ISM磁场相当强(B&gt；6mug)，这引发了一个问题，即超临界云核是如何产生的？回答这个问题是这个项目的目标。在这个拟议的项目中，我们将测试这个问题的两种可能的答案，即双极扩散(AD)介导的过程和积累过程，在AD过程中，局部质量流量增加，在积累过程中，气体被远距离聚集。因此，我们将详细研究影响AD模型的物理过程(例如，化学和辐射电离过程)，并将用全球星系模拟自洽地探索积累过程。

Magnetic fields are an elemental part of the interstellar medium (ISM) which have a large impact on the dynamics of the ISM on various spatial scales. One long-standing issue is their influence on the formation of stars in galaxies. Similarly to thermal pressure, magnetic fields prevent contraction of otherwise self-gravitating gas clumps if they are strong enough. Therefore, gaseous overdensities must be magnetically supercritical, quantified by the mass-to-flux ratio, to collapse and to subsequently allow the formation of stars. There is increasing evidence that the ISM-field is rather strong (B > 6 muG) which gives rise to the question how supercritical cloud cores can be generated? To answer this question is the goal of this project. Within this proposed project we will test the two possible answers to this issue, namely the ambipolar diffusion (AD) mediated process, where locally the mass-to-flux is increased and the accumulation process, where gas is gathered over large distances. Therefore, we will study in detail the physics which impacts the AD-model (e.g. chemical and radiative ionisation processes) and we will self-consistently probe the accumulation process with global galactic simulations.