Observational study of origin of the interstellar turbulence

我们通过高分辨率的12CO观测发现了分子云的小尺度结构。小尺度结构有更小的速度色散的光谱相比，在分子云的中间观察到的典型的。这意味着分子云不是均匀的实体，而是由冷的和密集的小尺度结构的热平衡，所建议的理论两相介质模型和热中性介质的热不稳定性。这些结果提供了关于分子云形成的线索，这是星际物理学的最大问题之一。阿尔马等对分子和原子气体的高角分辨率观测计划的后续工作将解决这些问题。

We discovered small-scale structures of molecular clouds by high-resolution 12CO observations. The small-scale structures have much smaller velocity dispersions of the spectra compared to typical ones observed in the middle of molecular clouds. These imply that molecular clouds are not uniform entities, but consist of cold and dense small-scale structures in the thermal equilibrium, as suggested by the theoretical two-phase medium model and thermal instability of the warm neutral medium. These results gave clues about molecular cloud formation, one of the biggest issues of the interstellar physics. The follow-up observations of molecular and atomic gas with high angular resolution by ALMA and others are scheduled to solve the problems.