Molecular shocks in the intersellar medium

分子云是气体和尘埃的巨大储存库，在重力作用下坍塌形成致密的恒星形成核心。当恒星形成时，会产生喷流和风，并与周围的分子云相互作用。然后冲击被驱动到云层中，卷起物质。观测结果经常显示出弓形结构，但这些冲击的性质和结构在很大程度上取决于气体和磁场的局部电离分数。流出的反馈决定了恒星是否继续在分子云中形成。通常，一氧化硅发射与通过分子云传播的冲击有关，它一直是广泛观测计划的主题。硅在气相中的存在是由于硅从尘埃颗粒和颗粒-颗粒相互作用的溅射。我们已经开发了一个随时间变化的数值代码来计算平面平行激波结构和由此产生的SiO发射从晶粒溅射。目前，颗粒间的相互作用并没有包含在程序中，颗粒是作为单一尺寸的流体而被包含的。制定和测试包含灰尘粒度分布的数值方法2。包括尘埃颗粒的过程，如颗粒颗粒碰撞。数值研究的结果可以与分子外流的观察。

Molecular clouds are large reservoirs of gas and dust, which collapse under gravity to form dense star-forming cores. As stars form, jets and winds are produced and interact with the molecular cloud surrounding them. Shocks are then driven into the clouds sweeping up material. Observations often reveal bow-shaped structures, but the nature and structure of these shocks depends strongly on the local ionisation fraction of the gas and the magnetic field. The feedback from the outflows determines whether stars continue to form within molecular clouds. Often SiO emission is associated with shocks propagating through molecular clouds and it has been the subject of extensive observational programs. The presence of silicon in the gas phase is attributed to sputtering of silicon from dust grains and to grain-grain interactions. We have developed a time-dependent numerical code to calculate plane-parallel shock structures and the resulting SiO emission from grain sputtering. Currently, grain-grain interactions are not included in the code, and grains are included as single-sized fluids.The aims of this project are: 1. to formulate and test a numerical method for the inclusion of dust grain-size distributions2. to include dust grain processes, such as grain-grain collisions.The results of the numerical studies can be compared with observations of molecular outflows.