论文标题
紫外线外行传输光谱特征作为金属和雨的探针
UV Exoplanet Transmission Spectral Features as Probes of Metals and Rainout
论文作者
论文摘要
超热木星的低分辨率透射光谱观察到了0.5微米的近距离表明在短波长下吸收强大。先前的解释包括散射，光化学，逃脱的金属和不平衡化学。在这封信中，我们表明，斜率和特征是0.5微米的偏差可能是由于在大气模型中通常不考虑的超级性能引起的，但如果条件接近化学平衡，则可以保证存在，包括Fe I，Fe I，Fe I，Ti I，Ni I，Ca I，Ca I，Ca II和Sio。即使是相对痕迹的物种（例如，Cr I和Mn I）也可以通过紫外线和蓝光的强线贡献。使用凤凰大气模型，我们描述了短波长的传输光谱如何随平衡温度在1000 K和4000 K之间的变化，以及冷凝水的雨水在这些波长下的影响。我们定义了两个光谱指标，以量化NUV和蓝色吸收的强度与红色光学相比，发现NUV的传输深度将显着超过单独的雷利散射中的雷利（Rayleigh）散射中的持续深度，所有热木星降低到1000 k左右。统治，如果存在。我们进一步表明，这些光谱指数可用于追踪Rainout的影响。然后，我们将模拟的过境光谱与WASP-12b，WASP-33B，WASP-76B和WASP-121B的现有观察结果进行比较。
The low-resolution transmission spectra of ultra-hot Jupiters observed shortward of 0.5 microns indicate strong absorption at short-wavelengths. Previous explanations have included scattering, photochemistry, escaping metals, and disequilibrium chemistry. In this Letter, we show that slopes and features shortward of 0.5 microns can be caused by opacity not commonly considered in atmosphere models of exoplanets but guaranteed to be present if conditions are near chemical equilibrium including Fe I, Fe II, Ti I, Ni I, Ca I, Ca II, and SiO. Even relatively trace species (e.g., Cr I and Mn I) can contribute through strong lines in the UV and blue-optical. Using the PHOENIX atmosphere model, we describe how the short-wavelength transit spectrum varies with equilibrium temperature between 1000 K and 4000 K, as well as the effect that the rainout of condensates has at these wavelengths. We define two spectral indices to quantify the strength of the NUV and blue absorption compared to that in the red-optical, finding that the NUV transit depth will significantly exceed the transit depth from Rayleigh scattering alone for all hot Jupiters down to around 1000 K. In the blue-optical, hot Jupiters warmer than 2000 K will have transit depths larger than that from Rayleigh scattering, but below 2000 K, Rayleigh scattering can dominate, if present. We further show that these spectral indices may be used to trace the effects of rainout. We then compare our simulated transit spectra to existing observations of WASP-12b, WASP-33b, WASP-76b, and WASP-121b.
