标题： 由于湍流的存在而变得稳定的“不稳定自然介质” 显示英文标题

标题： The stable "Unstable Natural Media" due to the presence of turbulence

摘要： 术语“不稳定中性介质”（UNM）传统上被用来描述形成于暖中性氢（HI）相和冷中性氢相之间的瞬态阶段，并且并非HI研究的重点。然而，最近的观测表明，UNM相不仅具有比预期更长得多的寿命，而且至少占据了HI体积和质量分数的20%到40%。本文中，我们通过能量平衡论证提出，强湍流的存在可以解释UNM的存在及其主导地位。UNM的质量分数与湍流速度弥散量 $\sigma_v$ 成正比：UNM的质量分数为 $\propto \sigma_v^{\frac{2n}{1+n}}$，其中 $n$ 是不稳定相绝热指数的绝对值。我们讨论了长期存在的不稳定热相在星际介质物理中的意义，包括冷密丝状结构的形成、宇宙射线加速以及银河前景统计测量。 显示英文摘要

摘要： The term "unstable neutral media" (UNM) has traditionally been used to describe the transient phase formed between the warm and cold neutral hydrogen (HI) phases and has not been the focus of HI studies. However, recent observations suggest that the UNM phase not only has a significantly longer-than-expected lifetime but also occupies at least 20\% to 40\% of both the volume and mass fraction of HI. In this paper, we argue that the existence and dominance of the UNM can be explained by the presence of strong turbulence using an energy balance argument. The mass fraction of UNM is directly proportional to the turbulent velocity dispersion $\sigma_v$: mass fraction of UNM $\propto \sigma_v^{\frac{2n}{1+n}}$, where $n$ is the absolute value of the adiabatic index in the unstable phase. We discuss the implications of long-lived unstable thermal phases on ISM physics, including cold dense filament formation, cosmic ray acceleration, and measurement of galactic foreground statistics.