论文标题
行星星云中的低电离结构-II。 6个PNE的密度，温度，丰度和激发
Low-ionization structures in planetary nebulae -- II. Densities, temperatures, abundances and excitation of 6 PNe
论文作者
论文摘要
在这里，我们介绍了六个银河星云（PNE）的空间解决研究，即IC 4593，Hen 2-186，Hen 2-429，NGC 3918，NGC 3918，NGC 6543和NGC 6905，来自2.5 M ISAAC Newth Newth Telesscope的中间分辨率光谱和NGC 6905。物理条件（电子密度，n $ _ {e} $和温度，t $ _ {e} $），这些物体不同区域的化学成分和主要的激发机制是得出的，以更深入地了解这些PNE所主持的低离子化结构（LISS）的知识。我们加强了先前的结论，即LIS的特征是比其关联的边缘和外壳低（或最多等于）n $ _ {e} $。至于t $ _ {e} $，我们指出了N和O诊断之间的不同趋势。 t $ _e $ [nii]在整个黑色组件中没有显示显着的变化，而T $ _e $ [oiii]对于LIS来说似乎略高。 LISS的T $ _e $ [OIII]相关的更大的不确定性不允许结论。此外，化学丰度从一个到另一个PN组件没有变化，甚至没有将LIS与轮辋和壳形成对比，也没有在许多其他作品中发现。通过讨论由于冲击和恒星辐射引起的电离光子通量，我们探索了导致LISS激发的可能机制。我们认为，尽管对宿主pne和liss的方向有很大的依赖，但LIS中的冲击没有忽略不计。
Here we present the spatially resolved study of six Galactic planetary nebulae (PNe), namely IC 4593, Hen 2-186, Hen 2-429, NGC 3918, NGC 6543 and NGC 6905, from intermediate-resolution spectra of the 2.5 m Isaac Newton Telescope and the 1.54 m Danish telescope. The physical conditions (electron densities, N$_{e}$, and temperatures, T$_{e}$), chemical compositions and dominant excitation mechanisms for the different regions of these objects are derived, in an attempt to go deeper on the knowledge of the low-ionization structures (LISs) hosted by these PNe. We reinforce the previous conclusions that LISs are characterized by lower (or at most equal) N$_{e}$ than their associated rims and shells. As for the T$_{e}$, we point out a \textit{possible} different trend between the N and O diagnostics. T$_e$[NII] does not show significant variations throughout the nebular components, whereas T$_e$[OIII] appears to be slightly higher for LISs. The much larger uncertainties associated with the T$_e$[OIII] of LISs do not allow robust conclusions. Moreover, the chemical abundances show no variation from one to another PN components, not even contrasting LISs with rims and shells, as also found in a number of other works. By discussing the ionization photon flux due to shocks and stellar radiation, we explore the possible mechanisms responsible for the excitation of LISs. We argue that the presence of shocks in LISs is not negligible, although there is a strong dependence on the orientation of the host PNe and LISs.
