近邻分子云恒星形成过程中引力和湍流的作用

引力与湍流的作用是恒星形成研究中的基本问题。主流的湍流调节模型认为湍流起主导作用，即湍流在大尺度上阻止了分子云的自由坍缩，但在小尺度上引发了恒星形成，而恒星形成是一个缓慢平稳的过程。但最新的整体层级坍缩模型则认为引力起主导作用，分子云整体上处于各向异性的坍缩状态，恒星形成是一个快速且随时间演化的过程。这两种模型预言了不同的恒星形成过程。本项目计划使用“银河画卷”巡天数据和公开数据在以下三方面对近邻分子云展开统计分析：i)分子云的层级结构与分子谱线线宽之间的关系；ii)分子云的恒星形成率随时间的变化；iii)分子云中年轻星及其性质的空间分布。将统计结果与湍流调节模型和整体层级坍缩模型分别比较，就可以对这两种模型给出观测限制。实际上，湍流调节模型代表一种看待恒星形成的静态平衡的观点，而整体层级坍缩模型则代表一种动态演化的观点，对这两种模型的观测研究和检验有可能深刻改变我们对恒星形成的理解。

The relative importance of self-gravity and turbulence is a basic question in star formation studies. The well-known turbulence-regulated model relies on control by driven supersonic turbulence which can, on the one hand, provide global support, and on the other hand, produce density enhancements that allow local collapse. The turbulence-regulated model predicts a quasi-stationary star formation process. In contrast, the new global hierarchical collapse (GHC) model gives another unified description of star formation scenario. GHC offers a flow regime of collapse within collapse, in which self-gravity plays a dominant role and all scales accrete from their parent structures through the filamentary material flows. GHC predicts a dynamic and evolutionary star formation process. Thus the turbulence-regulated and GHC models predict different star formation processes. We propose to investigate i) the relation between the hierarchical structures of molecular clouds and molecular line width; ii) the time-dependent star formation rate (SFR); iii) the spatial distribution of young stellar objects (YSOs) and their properties; in the nearby molecular clouds with the aim to test and observationally constrain the turbulence-regulated and GHC models by comparing the above investigations with the predictions of those two models. In fact, the turbulence-regulated model represents a stationary and equilibrious view of star formation while the GHC represents a dynamic and evolutionary view. We believe that the detailed analysis and observationally test for these two models could reinvent the understanding of star formation.