标题： HII区周围支柱形成的详细数值模拟 显示英文标题

标题： Detailed Numerical Simulations on the Formation of Pillars around HII-regions

摘要： 我们研究了分子云的湍流结构演化，在附近大质量恒星发出的电离辐射影响下，利用iVINE代码进行了高分辨率参数研究。温度设定为10 K或100 K，平均数密度为100 cm⁻³ 或 300 cm⁻³。此外，湍流速度从马赫数1.5变化到12.5，主驱动尺度在1 pc到8 pc之间。我们通过一个数量级的变化调整电离通量。在我们的模拟中，电离辐射增强了初始湍动的密度分布，从而自然地形成了与HII区相邻的柱状结构。这些结构的尖端经常发生引力坍缩。我们发现湍动冷云的初始状态与形成结构的最终形态和物理属性之间存在明确的相关性。柱状结构形成的最有利条件是马赫数4到10之间。只有当高密度未电离气体与即将被电离的气体之间的初始密度对比小于热气体与冷气体之间的温度对比时，结构和相应的恒星才会形成。柱状结构的密度由热气与冷气之间的压力平衡决定。对模拟的详细分析表明，形成的细长丝状结构的复杂动力学和几何结构以令人印象深刻的程度反映了观测到的柱状结构。此外，我们发现观测到的视线速度可以明确区分不同的形成机制。将当前模拟结果与先前结果及最近的观测进行比较后，我们得出结论，例如，M16中的“创生之柱”是由这里提出的机制形成，而不是由预存团块的辐射驱动塌缩形成。 显示英文摘要

摘要： We study the structural evolution of turbulent molecular clouds under the influence of ionizing radiation emitted from a nearby massive star by performing a high resolution parameter study with the iVINE code. The temperature is taken to be 10K or 100K, the mean number density is either 100cm^3 or 300cm^3. Besides, the turbulence is varied between Mach 1.5 and Mach 12.5 and the main driving scale between 1pc and 8pc. We vary the ionizing flux by an order of magnitude. In our simulations the ionizing radiation enhances the initial turbulent density distribution and thus leads to the formation of pillar-like structures observed adjacent to HII regions in a natural way. Gravitational collapse occurs regularly at the tips of the structures. We find a clear correlation between the initial state of the turbulent cold cloud and the final morphology and physical properties of the structures formed. The most favorable regime for the formation of pillars is Mach 4-10. Structures and therefore stars only form if the initial density contrast between the high density unionized gas and the gas that is going to be ionized is lower than the temperature contrast between the hot and the cold gas. The density of the resulting pillars is determined by a pressure equilibrium between the hot and the cold gas. A thorough analysis of the simulations shows that the complex kinematical and geometrical structure of the formed elongated filaments reflects that of observed pillars to an impressive level of detail. In addition, we find that the observed line-of sight velocities allow for a distinct determination of different formation mechanisms. Comparing the current simulations to previous results and recent observations we conclude that e.g. the pillars of creation in M16 formed by the mechanism proposed here and not by the radiation driven implosion of pre-existing clumps.