The discovery of exoplanets and the desire to understand their atmospheric chemical composition and habitability provides a new rationale for understanding the radiation from X-rays to radio wavelengths emitted by their host stars. Semiempirical models of stellar atmospheres that include accurate treatment of radiative transfer of all important atoms, ions, and molecules provide the essential basis for understanding a star's emitted radiation that is our main data source for characterizing a star and the radiation environment of its exoplanets. In Solar-type and cooler stars, the ultraviolet and extreme ultraviolet radiation formed in their chromospheres and transition regions drive the photochemistry in exoplanet atmospheres. In this review, I describe and critique the development of semiempirical static and time-dependent models of the chromospheres and transition regions of the Sun and cooler stars as well as the spectroscopic diagnostics upon which these models are based. The related topics of stellar...

中文翻译：

---

恒星模型色球和光谱诊断

系外行星的发现以及了解它们大气化学成分和宜居性的愿望为理解从 X 射线到其宿主恒星发出的无线电波长的辐射提供了新的理论基础。恒星大气的半经验模型包括对所有重要原子、离子和分子的辐射转移的准确处理，为理解恒星发出的辐射提供了必要的基础，这是我们表征恒星及其系外行星辐射环境的主要数据来源。在太阳型和较冷的恒星中，在它们的色球层和过渡区形成的紫外线和极紫外线辐射驱动着系外行星大气中的光化学。在这次审查中，我描述并批评了太阳和较冷恒星的色球层和过渡区的半经验静态和时间相关模型的发展，以及这些模型所基于的光谱诊断。恒星的相关话题...