Gravitationally bound gas determines star formation in the Galaxy

作者：Sihan Jiao, Jingwen Wu, Zhi-Yu Zhang, Neal J. Evans, Chao‐Wei Tsai, Di Li, Hauyu Baobab Liu, Yong Shi, Junzhi Wang, Qizhou Zhang, Yuxin Lin, Linjing Feng, Xing Lu, Yan Sun, Hao Ruan, F. S. Deng · 发表于：Astronomy and Astrophysics · 年份：2025 · DOI：10.1051/0004-6361/202453608 · 被引用次数：7 · 研究领域：Astrophysics and Star Formation Studies、Stellar, planetary, and galactic studies、Galaxies: Formation, Evolution, Phenomena

Stars form from molecular gas under complex conditions influenced by multiple competing physical mechanisms, such as gravity, turbulence, and magnetic fields. However, accurately identifying the fraction of gas actively involved in star formation remains challenging. Using dust continuum observations from the Herschel Space Observatory, we derived column density maps and their associated probability distribution functions (N-PDFs). Assuming that the power-law component in the N-PDFs corresponds to gravitationally bound (and thus star-forming) gas, we analyzed a diverse sample of molecular clouds spanning a wide range of mass and turbulence conditions. This sample included 21 molecular clouds from the solar neighborhood ( d < 500 pc) and 16 high-mass star-forming molecular clouds. For these two groups, we employed the counts of young stellar objects (YSOs) and mid to far-infrared luminosities as proxies for star formation rates (SFRs), respectively. Both groups revealed a tight linear correlation between the mass of the gravitationally bound gas and the SFR, suggesting a universally constant star formation efficiency in the gravitationally bound gas phase. The star-forming gas mass derived from threshold column densities ( N threshold ) varies from cloud to cloud and is widely distributed over the range of ~1–17×10 21 cm −2 based on N-PDF analysis. However, in solar neighborhood clouds it is in rough consistency with the traditional approach using A V ≥ 8 mag. In contrast, ...