AI 中文总结
研究通过结合多种数据与模型对本地星际介质热相进行三维重建，揭示了冷云及其热不稳定包层等结构，发现部分质量热不稳定且冷相密度分布窄，为多相星际介质提供证据，推动重新评估恒星形成模型。
AI 中文摘要
星际气体的热状态决定其是保持温暖弥散还是冷却成致密云。21厘米观测已建立中性气体相的统计图像，但此前其三维结构未被测绘。本文展示了$\mathcal{P}_{\rm 3D}$，即本地星际介质热相的三维重建，覆盖以太阳为中心直径1千秒差距的区域，在2秒差距的笛卡尔网格上采样。它结合了尘埃消光和星际远紫外线辐射的高分辨率三维地图以及中性星际介质热化学模型。重建显示冷云被热不稳定包层包围并嵌入普遍的温暖相中。在距银河中平面$|z| \leq 150$秒差距内，约41%的尘埃追踪中性质量是热不稳定的，意味着在约2.9 - 6百万年的时间尺度上有相循环。冷相密度分布窄，与内部马赫数至多为跨音速相符。这些发现支持动态循环的多相星际介质，并促使重新评估假设单相、强超音速冷气体密度场的恒星形成模型。
英文摘要
The thermal state of interstellar gas controls whether it remains warm and diffuse or cools into dense clouds. Twenty-one centimetre observations have established a statistical picture of neutral-gas phases, but their three-dimensional architecture has not previously been mapped. Here we present $\mathcal{P}_{\rm 3D}$, a three-dimensional reconstruction of thermal phase in the local interstellar medium (ISM), covering a 1 kpc-diameter region centred on the Sun and sampled on a 2 pc Cartesian grid. $\mathcal{P}_{\rm 3D}$ combines high-resolution 3D maps of dust extinction and interstellar far-ultraviolet radiation with a neutral-ISM thermochemical model. The reconstruction reveals cold clouds surrounded by thermally unstable envelopes and embedded in a pervasive warm phase. Within $|z| \leq 150$ pc of the Galactic midplane, $\sim$41 % of the dust-traced neutral mass is thermally unstable, implying phase cycling on a timescale of $\sim$2.9-6 Myr. Yet the cold phase has a narrow density distribution, consistent with internal Mach numbers that are transonic at most ($\mathcal{M}_s \lesssim 1.5$). Together, these findings favour a dynamically cycling multiphase interstellar medium and motivate reassessing star-formation models that assume a single-phase, strongly supersonic cold-gas density field.
CommentsUnder peer review at Nature Astronomy. Constructive comments are welcome
