The ionization of hydrogen in the solar chromosphere and transition region does not obey LTE or instantaneous statistical equilibrium because the timescale is long compared with important hydrodynamical timescales, especially of magneto-acoustic shocks. We implement an algorithm to compute non-equilibrium hydrogen ionization and its coupling into the MHD equations within an existing radiation MHD code, and perform a two-dimensional simulation of the solar atmosphere from the convection zone to the corona. Analysis of the simulation results and comparison to a companion simulation assuming LTE shows that: a) Non-equilibrium computation delivers much smaller variations of the chromospheric hydrogen ionization than for LTE. The ionization is smaller within shocks but subsequently remains high in the cool intershock phases. As a result, the chromospheric temperature variations are much larger than for LTE because in non-equilibrium, hydrogen ionization is a less effective internal energy buffer. The actual shock temperatures are therefore higher and the intershock temperatures lower. b) The chromospheric populations of the hydrogen n = 2 level, which governs the opacity of Halpha, are coupled to the ion populations. They are set by the high temperature in shocks and subsequently remain high in the cool intershock phases. c) The temperature structure and the hydrogen level populations differ much between the chromosphere above photospheric magnetic elements and above quiet internetwork. d) The hydrogen n = 2 population and column density are persistently high in dynamic fibrils, suggesting that these obtain their visibility from being optically thick in Halpha also at low temperature.
The Atmospheric Signatures of Super-Earths: How to Distinguish Between Hydrogen-Rich and Hydrogen-Poor Atmospheres
太阳系外的超级地球（1-10 M $_{\earth}$）很可能存在广泛的大气层。一些超级地球可能能够保留大量富含氢的大气层。其他行星可能永远不会积累氢或经历轻质元素的大量逃逸，导致大气层更像我们太阳系中的类地行星。我们研究了观察者如何通过模拟超地球发射光谱和透射光谱来区分富氢和贫氢大气，并且我们发现仅通过观察透射光谱就可以区分富氢和贫氢大气。一个类似地球的大气层，主要由重元素和分子组成，由于它的大气尺度高度很小（因为尺度高度与分子量成反比），因此传输信号非常弱。另一方面，一个大的富氢大气揭示了一个相对较大的传输信号。超级地球的发射光谱还可以控制大气成分和温度结构。具有大量氢大气层的超级地球将由于水而显示出强烈的光谱特征，而那些已经失去大部分氢（并且没有液态海洋）的超级地球将以CO $_2$特征和缺乏H $_2$ O为标志。我们将我们的研究具体应用于围绕M星运行的低质量行星Gl 581 c（$M sin i$ = 5 M $_{\earth}$），尽管我们的结论与一般的超级地球有关。区分富氢大气层的能力对于解释岩石超级地球和海王星类行星之间过渡的行星质量和半径观测至关重要。
Equation of state and opacities for hydrogen atmospheres of magnetars
将部分电离强磁化氢等离子体的状态方程和辐射不透明度（磁场强度为8.e11 G < B < 3.e13 G）推广到磁场强度为3.e13 G <B < 1.e15 G的磁星.计算了5.e5 < T < 4.e7 K范围内的一阶、二阶热力学函数和辐射不透明度。我们表明，束缚-自由过渡给出了一个重要的贡献，在考虑范围内的B在外部中子星大气层的不透明度。与较弱场的情况不同，束缚-束缚跃迁并不重要。
Axi-symmetric Models of B[e] Supergiants: I. The Effective Temperature and Mass-loss Dependence of the Hydrogen and Helium Ionization Structure
我们计算了B[e]包层中的氢和氦电离，并探讨了它们对质量损失和有效温度的依赖性。我们还提出了模拟观测的H α发射线和C IV 1550的双重，并研究它们的行为。本文报道了我们正在进行的B[e]超巨星研究的第一个结果，并在自洽数值模拟中提供了最重要元素电离的一瞥。我们新开发的二维恒星大气程序，ASTAROTH，用于数值模拟。该代码自洽地解决了连续辐射，非LTE水平的人口，和电子温度轴对称恒星信封。观察到的配置文件进行了计算的辅助程序独立开发的ASTAROTH。在我们的所有模型中，除了一个模型之外，H仍然完全电离。由于从激发态电离，得到H中性盘比以前的分析计算要困难得多。在两极附近，电离在所有模型中都很高，而氦在赤道地区重新结合，但我们的质量损失率最低。虽然模型参数没有被调整以提供对任何特定恒星的拟合，但理论轮廓显示了R126轮廓中的一些特征。这些包括部分解析的双峰轮廓的H α，和弱发射与UV C IV共振线。
Scattering of X-ray emission lines by the neutral and molecular hydrogen in the Sun's atmosphere and in the vicinity of active galactic nuclei and compact sources
