AI 中文总结
本研究通过\textsc{SILCC}项目的磁流体力学模拟，发现本地泡内的类LLCC冷气体可在反馈驱动环境中原位非绝热冷却形成，无需作为预存冷物质输入，且能存活约2.5百万年。
AI 中文摘要
本地泡（LB）从太阳延伸约100--200秒差距（pc），包含温度为10^6 K的等离子体和温暖的光致电离气体。然而，本地利奥冷云（LLCC）和本地冷云带仅位于11--24 pc处，处于LB内部，温度接近20 K。这类冷物质如何在更热的环境中形成并存活至今仍不明确，基于暖云碰撞的解释也难以通过观测验证。我们研究类LLCC气体是在反馈驱动环境中局部聚集而成，还是必须作为预先存在的冷物质输入，以及其能否存活数百万年。我们使用来自\textsc{SILCC}项目的磁流体力学模拟，包含自洽的恒星形成、恒星风与超新星、电离和远紫外辐射、非平衡化学以及宇宙射线传输。我们识别出温度T<100 K、氢分子数密度0<n_\text{H₂}≤2 cm⁻³的冷弥散气体，并使用拉格朗日示踪粒子重建其聚集、冷却、存活和扩散过程。模拟在暖-热、反馈驱动的环境中产生了冷弥散气体，其中非热压力支撑至关重要。宇宙射线压力在冷气体界面几乎连续，形成压力底限，而磁压力部分抵消外部热压力过剩。这些结构在冷弥散相的持续时间中位数为2.5百万年（Myr），且大部分物质在失去空间相干性后仍保持低温。该气体可从附近冷且热不稳定的暖物质局部聚集而成，形成丝状或片状形态。冷却至约20 K并非由绝热膨胀驱动，而是由非绝热冷却驱动。因此，LLCC无需以已形成的冷云形式进入LB，类LLCC气体可在原位局部聚集并非绝热冷却。
英文摘要
The Local Bubble (LB) extends approximately 100--200~pc from the Sun and contains $10^6$~K plasma and warm photoionised gas. Yet the Local Leo Cold Cloud (LLCC) and the Local Ribbon of Cold Clouds lie only 11--24~pc away, well inside the LB, at temperatures near 20~K. How such cold material forms and survives in this hotter environment remains uncertain, and explanations based on colliding warm clouds are difficult to test observationally. We investigate whether LLCC-like gas can assemble locally in a feedback-driven environment or must be imported as pre-existing cold material, and whether it can survive for several Myr. We use magnetohydrodynamic simulations from the \textsc{SILCC} Project including self-consistent star formation, stellar winds and supernovae, ionising and far-ultraviolet radiation, non-equilibrium chemistry, and cosmic-ray transport. We identify cold diffuse gas with $T<100$~K and $0<n_\mathrm{H_2}\leq2$~cm$^{-3}$ and use Lagrangian tracers to reconstruct its assembly, cooling, survival, and dispersal. The simulations produce cold diffuse gas in warm--hot, feedback-driven surroundings, where non-thermal pressure support is crucial. Cosmic-ray pressure remains nearly continuous across cold-gas interfaces and establishes a pressure floor, while magnetic pressure partly offsets the external thermal-pressure excess. The structures persist in the cold diffuse phase for a median of 2.5~Myr, and most of their material remains cold after they lose spatial coherence. The gas can assemble locally from nearby cold and thermally unstable warm material, developing filamentary or sheet-like morphologies. Cooling to $\sim20$~K is driven not by adiabatic expansion but by non-adiabatic cooling. The LLCC therefore need not have entered the LB as an already-formed cold cloud. LLCC-like gas can instead assemble and cool non-adiabatically in situ.
Comments14 pages, 11 figures, submitted to A&A, comments welcome
