A Study of Magnetic Fields in the Formation of Molecular Clouds and Stars

恒星由巨大的氢气云形成，但坍塌的细节仍不清楚。研究人员将使用计算机模型来模拟云坍塌形成恒星的过程。这位研究人员试图回答关于恒星形成的三个重要问题。(1)云在多大程度上变成了恒星？(2)这种情况发生的速度有多快？(3)磁场是促使气体崩塌的最重要的力量吗？研究人员将进行一系列合成观测，以寻找坍塌气体的第一个特征。恒星的形成需要数百万年的时间。天文学家对银河系中许多云层的观测是恒星形成历史的快照。计算机模型允许天文学家将所有这些观测整理成一个恒星诞生的故事。研究人员将产生一系列合成的全星系分子和银河系热气的地图。数值模式使用自适应网格优化，并包括磁场、辐射反馈和云化学成分模型的影响。开放源代码Enzo将用于模拟。模拟的物理尺度为1000个pC，分辨率为100个天文单位。研究人员将从类似于分层星系盘中看到的初始条件开始。在更高的线性分辨率下，模拟将集中在分子云和蕴藏着年轻恒星的密集核心上。将生成完整的力集合历史和观测签名。

Stars form out of giant clouds of hydrogen, but the details of the collapse are still unclear. The investigators will use computer models to simulate the collapses of clouds to form stars. The investigator seeks to answer three important questions concerning star formation. (1) How much of a cloud turns into stars? (2) How fast does this happen? (3) Are magnetic fields the most important force on collapsing gas? The investigator will produce a series of synthetic observations to hunt for the very first signature of collapsing gas. Star formation of takes millions of years. Astronomer's observations of many clouds in our galaxy are snap shots of the history of star formation. The computer models allow astronomers to organize all these observations into a single story of the birth of stars.The investigator will produce a sequence of synthetic, all-galaxy, maps of molecules and hot gas in our galaxy. The numerical models use adaptive mesh refinement and include the effects of magnetic fields, radiation feedback, and models for the chemical composition of the clouds. The open source code ENZO will be used for the simulations. The simulations have a physical scale of 1000 pc and resolution of 100 astronomical units. The investigator will start with initial conditions similar to those seen in the stratified galactic disk. At higher linear resolution, the simulation will be concentrated on molecular clouds and the dense cores that harbor young stars. The complete assembly history of forces and observational signatures will be produced.