湍流巨分子云的天体化学演化：I -流体动力学嵌入无星云的物理过程和求解方法
The Astrochemical Evolution of Turbulent Giant Molecular Clouds : I - Physical Processes and Method of Solution for Hydrodynamic, Embedded Starless Clouds
摘要：
当代银河系恒星的形成主要发生在超音速、湍流、磁化的巨分子云（GMC）中引力不稳定、寒冷、致密的分子气体中。值得注意的是，因为化学演化时标和湍流涡旋周转时标在典型的GMC条件下是相当的，分子通过固有的非平衡化学演化，这是强烈耦合到云的动态演化。目前的数值模拟技术，其中包括最多三十年的长度尺度，可以刚刚开始弥合超音速湍流GMC的全球动力学时间之间的鸿沟，其背景湍流的薄激波后冷却层内的热和化学演化。我们解决这个GMC天体化学尺度的问题，使用的解决方案的方法，它允许复杂的三维湍流动力学以及准确的处理非平衡后冲击热力学和化学。我们目前的方法在更大范围的物理过程的背景下，重要的了解GMCs的化学演变，包括气相化学，尘埃颗粒和表面化学，和湍流加热。我们提出了一个新的拉格朗日验证试验超音速湍流的结果。我们根据无量纲的当地冲击后Damköhler数，它量化的比例的动力学时间在冲击后冷却流的化学反应时间的给定物种的演变的特点。最后，我们讨论了这项工作的影响，GMC分子示踪剂的选择，和GMC核心的化学钟归零。
英文摘要：
Contemporary galactic star formation occurs predominantly within gravitationally unstable, cold, dense molecular gas within supersonic, turbulent, magnetized giant molecular clouds (GMCs). Significantly, because the chemical evolution timescale and the turbulent eddy-turnover timescale are comparable at typical GMC conditions, molecules evolve via inherently non-equilibrium chemistry which is strongly coupled to the dynamical evolution of the cloud. Current numerical simulation techniques, which include at most three decades in length scale, can just begin to bridge the divide between the global dynamical time of supersonic turbulent GMCs, and the thermal and chemical evolution within the thin post-shock cooling layers of their background turbulence. We address this GMC astrochemical scales problem using a solution methodology, which permits both complex three-dimensional turbulent dynamics as well as accurate treatment of non-equilibrium post-shock thermodynamics and chemistry. We present the current methodology in the context of the larger scope of physical processes important in understanding the chemical evolution of GMCs, including gas-phase chemistry, dust grains and surface chemistry, and turbulent heating. We present results of a new Lagrangian verification test for supersonic turbulence. We characterize the evolution of these species according to the dimensionless local post-shock Damköhler number, which quantifies the ratio of the dynamical time in the post-shock cooling flow to the chemical reaction time of a given species. Lastly, we discuss implications of this work to the selection of GMC molecular tracers, and the zeroing of chemical clocks of GMC cores.
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