论文标题
HD209458B的非本地热力学均衡传输频谱建模
Non-Local Thermodynamic Equilibrium Transmission Spectrum Modelling of HD209458b
论文作者
论文摘要
上下文 - 射层上层大气是辐射过程可以与碰撞过程竞争的低密度环境，并将非本地热力学平衡（NLTE）效应引入传输光谱。 目的 - 我们开发了一个NLTE辐射转移框架，能够在广泛的行星特性上对超球星透射光谱进行建模。 方法 - 我们适应了NLTE光谱合成代码的云层，以在NLTE和局部热力学平衡（LTE）中为热木星HD209458B产生大气结构和原子传递光谱，鉴于已发表的T -P轮廓和假设太阳金属性。将选定的光谱功能（包括H $α$，NA I D，He i $λ$ 10830，Fe I＆II Ultra-Violet（UV）频段以及C，O和Si UV系列）与文献观测值和模型进行了比较。测量了NLTE效应的强度，以确定哪些特征受到最大影响。 结果 - 开发的建模框架计算NLTE合成光谱将重现He i $λ$ 10830三重序，NA I D线的文献结果，以及光学中的Fe I森林。相对于LTE光谱，NLTE光谱中的各个光谱线表现出高达40％的吸收。
Context - Exoplanetary upper atmospheres are low density environments where radiative processes can compete with collisional ones and introduce non-local thermodynamic equilibrium (NLTE) effects into transmission spectra. Aims - We develop a NLTE radiative transfer framework capable of modelling exoplanetary transmission spectra over a wide range of planetary properties. Methods - We adapt the NLTE spectral synthesis code Cloudy to produce an atmospheric structure and atomic transmission spectrum in both NLTE and local thermodynamic equilibrium (LTE) for the hot Jupiter HD209458b, given a published T-P profile and assuming solar metallicity. Selected spectral features, including H$α$, Na I D, He I $λ$10830, Fe I & II ultra-violet (UV) bands, and C, O and Si UV lines, are compared with literature observations and models where available. The strength of NLTE effects are measured for individual spectral lines to identify which features are most strongly affected. Results - The developed modelling framework computing NLTE synthetic spectra reproduces literature results for the He I $λ$10830 triplet, the Na I D lines, and the forest of Fe I lines in the optical. Individual spectral lines in the NLTE spectrum exhibit up to 40 % stronger absorption relative to the LTE spectrum.
