标题： 检测[C I] $λ$8727 发射线。 NGC 7009中的低电离结构 显示英文标题

标题： Detection of the [C I] $λ$8727 emission line. Low-ionization structures in NGC 7009

摘要： 我们报告了首次对行星状星云 NGC 7009 中低电离结构外层对的近红外 [C I]$\lambda$8727 发射的空间分辨探测，这些数据来自多单元光谱探测器积分场单元获得的数据。 这种原子碳发射标志着电离气体与中性气体之间的过渡区域，并首次直接证明低电离结构 (LISs) 是光主导区域。 外层 LIS 对显示出强烈的 [C I]$\lambda$8727 发射，但 He I$\lambda$8733 缺失。 相反，内层结对显示出两条谱线，可能是由于星云本身的发射。 此外，主机星云发射中不存在 [C I]$\lambda$8727 谱线，但存在 He I$\lambda$8733。 尽管 [C I]$\lambda$8727 谱线的起源仍有争议，但其检测支持光蒸发致密分子团块的情景。 显示英文摘要

摘要： We report the first spatially resolved detection of the near-infrared [C I] $\lambda$8727 emission from the outer pair of low-ionization structures in the planetary nebula NGC 7009 from data obtained by the Multi Unit Spectroscopic Explorer integral field unit. This atomic carbon emission marks the transition zone between ionized and neutral gas, and for the first time offers direct evidence that LISs are photodominated regions. The outer LIS pair exhibits intense [C I] $\lambda$8727 emission, but He I $\lambda$8733 is absent. Conversely, the inner pair of knots shows both lines, likely due to the host nebula emission. Furthermore, the [C I] $\lambda$8727 line is absent in the host nebula emission, but He I $\lambda$8733 is present. Although the origin of the [C I] $\lambda$8727 line is still debated, its detection supports the scenario of photoevaporated dense molecular clumps.