气态星云中巴耳末线的荧光激发：案例D
Fluorescent excitation of Balmer lines in gaseous nebulae: case D
摘要：
非电离恒星连续体是氢莱曼跃迁中连续体泵浦的光子源。在这些跃迁的光学厚度较大的环境中，通过更高的串联谱线发生去激发，使得这些谱线中的通量除了复合之外还具有荧光贡献;特别地，巴耳末发射率在情况B以上系统地增强。这种机制在HII区的有效性和光电离模型作为研究它的工具的适当性是本工作的两个主要焦点。我们发现，低分辨率的人口合成模型照明的H II区域的光电离模型显着高估的荧光贡献的巴耳末线。相反，光电离模型，其中的连续的非电离部分被省略或不转移低估的荧光贡献的巴耳末线，产生类似的幅度在相反方向的偏置。在本文中，我们进行了现实的荧光巴耳末强度的估计，并讨论了变化的预期模拟观测设置和恒星人口的参数是不同的。在所有探索的情况下，我们发现，荧光激发提供了显着的贡献。我们还表明，差分荧光增强可能产生的视线差异的巴耳末减量，模仿星际灭绝。荧光激发出现从我们的研究作为一个小的，但重要的机制，增强巴耳末线，这应该考虑到在光电离区域的丰度分析，特别是在高精度的应用，如原始氦的测定的情况下。
英文摘要：
(abridged) Non-ionizing stellar continua are a source of photons for continuum pumping in the hydrogen Lyman transitions. In the environments where these transitions are optically thick, deexcitation occurs through higher series lines, so that the flux in these lines has a fluorescent contribution in addition to recombination; in particular, Balmer emissivities are systematically enhanced above case B. The effectiveness of such mechanism in HII regions and the adequacy of photoionization models as a tool to study it are the two main focuses of this work. We find that photoionization models of H II regions illuminated by low-resolution population synthesis models significantly overpredict the fluorescent contribution to the Balmer lines. Conversely, photoionization models in which the non-ionizing part of the continuum is omitted or is not transferred underpredict the fluorescent contribution to the Balmer lines, producing a bias of similar amplitude in the opposite direction. In this paper, we carry out realistic estimations of the fluorescent Balmer intensity and discuss the variations to be expected as the simulated observational setup and the stellar population's parameters are varied. In all the cases explored, we find that fluorescent excitation provides a significant contribution. We also show that differential fluorescent enhancement may produce line-of-sight differences in the Balmer decrement, mimicking interstellar extinction. Fluorescent excitation emerges from our study as a small but important mechanism for the enhancement of Balmer lines, which should be taken into account in the abundance analysis of photoionized regions, particularly in the case of high-precision applications such as the determination of primordial helium.
机构、总结、中文摘要均由AI分析而来，可能存在错误，请以论文正文为准。
