Star formation in transient molecular clouds
Star formation in transient molecular clouds
复制标题
瞬态分子云中的恒星形成
DOI：
10.1111/j.1365-2966.2004.07377.x
复制
发表时间：
2003
影响因子：
4.8
通讯作者：
I. Bonnell
中科院分区：
文献类型：
--
作者：
P. Clark;I. Bonnell
我们提出了一个数值模拟的结果，其中恒星的形成是从一个最初未结合的分子云核心开始的。主导动力学的湍流运动在激波中消散，留下一个静止区域，该区域受到引力束缚并坍塌形成一个小的多重系统。与此同时，云的大部分由于其初始超音速而逃逸。在这个模拟中，这个过程自然导致恒星形成效率为50%。恒星形成所涉及的质量取决于在冲击中耗散足够动能的气体比例。因此，具有较大湍流运动的云将导致较低的恒星形成效率。这意味着，在没有磁场或反馈过程的情况下，全球未结合的瞬态巨分子云（GMCs）可以解释我们银河系中观测到的恒星形成效率低的原因。对分子区域动态稳定性的观察表明，gmc可能不是自引力的，这支持了这封信中提出的观点。
We present the results of a numerical simulation in which star formation proceeds from an initially unbound molecular cloud core. The turbulent motions, which dominate the dynamics, dissipate in shocks leaving a quiescent region which becomes gravitationally bound and collapses to form a small multiple system. Meanwhile, the bulk of the cloud escapes due to its initial supersonic velocities. In this simulation, the process naturally results in a star formation efficiency of ∼50 per cent. The mass involved in star formation depends on the gas fraction that dissipates sufficient kinetic energy in shocks. Thus, clouds with larger turbulent motions will result in lower star formation efficiencies. This implies that globally unbound, and therefore transient giant molecular clouds (GMCs), can account for the low efficiency of star formation observed in our Galaxy without recourse to magnetic fields or feedback processes. Observations of the dynamic stability in molecular regions suggest that GMCs may not be self-gravitating, supporting the ideas presented in this letter.