One of the most important and well-established empirical results in astronomy is the Kennicutt–Schmidt relation between the density of interstellar gas and the rate at which that gas forms stars. A tight correlation between these quantities has long been measured at galactic scales. More recently, using surveys of YSOs, a KS relationship has been found within molecular clouds relating the surface density of star formation to the surface density of gas; however, the scaling of these laws varies significantly from cloud to cloud. In this Letter, we use a recently developed, high-accuracy catalog of young stellar objects from Spitzer combined with high-dynamic-range gas column density maps of 12 nearby (<1.5 kpc) molecular clouds from Herschel to re-examine the KS relation within individual molecular clouds. We find a tight, linear correlation between clouds’ star formation rate per unit area and their gas surface density normalized by the gas freefall time. The measured intracloud KS relation, which relates star formation rate to the volume density, extends over more than two orders of magnitude within each cloud and is nearly identical in each of the 12 clouds, implying a constant star formation efficiency per freefall time ϵ _ff ≈ 0.026. The finding of a universal correlation within individual molecular clouds, including clouds that contain no massive stars or massive stellar feedback, favors models in which star formation is regulated by local processes such as turbulence or stellar feedback such as protostellar outflows, and disfavors models in which star formation is regulated only by galaxy properties or supernova feedback on galactic scales.

天文学中最重要和最完善的经验结果之一是星际气体密度与气体形成恒星的速率之间的肯尼库特-施密特关系。长期以来，人们一直在银河尺度上测量这些量之间的紧密相关性。最近，通过对 YSO 的调查，在分子云中发现了 KS 关系，将恒星形成的表面密度与气体的表面密度联系起来；然而，这些定律的扩展因云而异。在这封信中，我们使用最近开发的来自斯皮策的年轻恒星物体的高精度目录，结合来自赫歇尔的 12 个附近（<1.5 kpc）分子云的高动态范围气柱密度图来重新检查 KS 关系在单个分子云中。我们发现一个紧，云的单位面积恒星形成率与其气体表面密度之间的线性相关性，由气体自由落体时间归一化。测得的云内 KS 关系将恒星形成率与体积密度联系起来，在每个云内延伸超过两个数量级，并且在 12 个云中的每一个中几乎相同，这意味着每个自由落体时间的恒星形成效率恒定ϵ _ff ≈ 0.026。在单个分子云（包括不包含大质量恒星或大质量恒星反馈的云）中发现普遍相关性，有利于恒星形成受局部过程（如湍流或恒星反馈（如原恒星外流）调节）的模型，而不赞成其中的模型恒星形成仅受星系属性或星系尺度上的超新星反馈调节。