AI 中文总结
本研究基于银河系内盘面45个分子云样本，探究云尺度恒星形成规律，发现恒星形成率与云质量近线性相关、效率随质量下降，且经典Kennicutt–Schmidt定律在单云尺度不显著，自由下落时间对恒星形成有重要调控作用。
AI 中文摘要
我们利用银河系内盘面中45个分子云（尺寸为5-240秒差距）的样本，研究了银河系的云尺度恒星形成，这些分子云的日心距离跨度为1.1-14.4千秒差距。我们通过¹²CO和¹³CO辐射推导这些云的质量，同时利用年轻恒星天体（YSO）族群估算恒星质量。研究的分子云质量范围约为10³到2.3×10⁶倍太阳质量（M☉），恒星形成效率（SFE）最高可达0.33。我们发现恒星形成率（SFR）与云的质量呈现紧密的近线性标度关系，这表明质量更大的云会按比例形成更多的恒星。然而，恒星形成效率（SFE）随云质量呈下降趋势。恒星形成率面密度（Σ_SFR）与气体面密度（Σ_gas）之间的关系存在显著的云间弥散，这表明在单个分子云的尺度上，经典的Kennicutt–Schmidt定律并未得到强验证。将云的自由下落时间（t_ff）纳入恒星形成标度关系后，凸显了其在调控恒星形成中的重要作用，不过观测到的关系表明，每自由下落时间的恒星形成效率并非普适。具体而言，恒星形成效率（SFE）随着每自由下落时间可用气体质量的增加而降低。我们结合近期关于分子云演化与恒星形成的理论模型，讨论了这些结果的启示意义。
英文摘要
We investigate cloud-scale star formation in the Milky Way using a sample of 45 molecular clouds (sizes of $5-240$ pc) in the inner Galactic plane, spanning heliocentric distances of $1.1-14.4$ kpc. Masses of these clouds are derived from $^{12}$CO and $^{13}$CO emission, while stellar masses are estimated using the young stellar object (YSO) population. The studied molecular clouds have masses ranging from $\sim10^{3}$ to $2.3\times10^{6}$ $\rm M_\odot$, with star formation efficiencies (SFE) up to 0.33. We find a tight, nearly linear scaling of the star formation rate (SFR) with the cloud mass, indicating that more massive clouds form proportionally more stars. The SFE, however, shows a declining trend with cloud mass. The relation between the star formation rate surface density ($Σ_{\rm SFR}$) and gas surface density ($Σ_{\rm gas}$) exhibits substantial cloud-to-cloud scatter, indicating that the canonical Kennicutt--Schmidt law is not strongly recovered at the scale of individual molecular clouds. Incorporating the cloud free-fall time ($\rm t_{ff}$) into the star formation scaling relation highlights its important role in regulating star formation, although the observed relations suggest that the star formation efficiency per free-fall time is not universal. In particular, the SFE decreases with increasing gas mass available per free-fall time. We discuss the implications of our results in the context of recent theoretical models of molecular cloud evolution and star formation.
Comments15 pages, 10 figures, Accepted for publication in ApJ
