We present the results of data analysis of the [C i] (³ P ₁–³ P ₀) emission from the ρ Ophiuchi A photon-dominated region (PDR) obtained in the ALMA ACA standalone mode with a spatial resolution of 2.″6 (360 au). The [C i] emission shows filamentary structures with a width of ∼1000 au, which are adjacent to the shell structure seen in the 4.5 μm map. We found that the 4.5 μm emission, C⁰, and CO are distributed in this order from the excitation star (S1) in a complementary pattern. These results indicate that [C i] is emitted from a thin layer in the PDR generated by the excitation star, as predicted in the plane-parallel PDR model. In addition, extended [C i] emission was also detected, which shows nearly uniform integrated intensity over the entire field of view (1.′6 1.′6). The line profile of the extended component is different from that of the above shell component. The column density ratio of C⁰ to CO in the extended component was ∼2, which is significantly higher than those of Galactic massive star-forming regions (0.1–0.2). These results suggest that [C i] is emitted also from the extended gas with a density of cm⁻³, which is not greatly affected by the excitation star.

我们展示了在空间分辨率为 2 的 ALMA ACA 独立模式中获得的ρ Ophiuchi A 光子主导区域 (PDR)的 [C i ] ( ³ P ₁ – ³ P ₀ ) 发射的数据分析结果。 6 (360 天文单位)。在[C我]发射显示丝状结构与〜1000 Au的宽度，这是相邻于4.5看到的壳结构μ米地图。我们发现，4.5 μ米发射，C ⁰，和CO分布在从以互补模式的激发星（S1）该顺序。这些结果表明 [C i] 从激发星产生的 PDR 中的薄层发射，如平面平行 PDR 模型中预测的那样。此外，还检测到扩展的 [C i ] 发射，在整个视场 (1.'6 1.'6) 上显示出几乎均匀的积分强度。扩展组件的线型轮廓与上述壳组件的线型轮廓不同。扩展成分中C ⁰与CO的柱密度比为~2，明显高于银河系大质量恒星形成区（0.1-0.2）。这些结果表明[C i ] 也是从密度为cm ^-3的扩展气体中发射出来的，它不受激发星的影响很大。