发表机构
University of Maryland; University of Chicago; Instituto de Astrofísica de Andalucía (IAA-CSIC); University of Birmingham; Carnegie Science; Space Telescope Science Institute; Peking University（马里兰大学; 芝加哥大学; 安达卢西亚天体物理研究所; 伯明翰大学; 卡内基科学研究所; 太空望远镜科学研究所; 北京大学）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究借助 JWST MIRI 对熔岩行星 TOI-431b 的部分次级食观测，发现其亮温度比符合存在大气层的特征，为该超高温岩质行星可能拥有大气层提供了观测依据。
AI 中文摘要
系外行星科学中一个悬而未决的问题是，距离宿主恒星极近的岩质系外行星（即“熔岩行星”）能否保留显著的大气层。通过次级食开展的热发射观测可用于确定岩质系外行星是否拥有大气层。据预测，大气层会提高行星的反照率和/或将热量从昼侧重新分配，从而降低测得的次级食深度。近期对熔岩行星（岩质行星，温度高到足以形成岩浆表面）的食观测已暗示大气层的存在。在此，我们报告了对熔岩行星 TOI-431b 的单次 JWST MIRI/LRS 部分次级食观测。我们测得食深度为 81 ± 16 ppm，对应亮温度为 1967⁺²³⁷₋₂₅₃ K，亮温度比 R = 0.81 ± 0.10，比斯皮策望远镜（Spitzer）报告的值高 1.2σ。观测到的亮温度比比反照率为零、热量重新分配为零的裸岩（R=1）低 1.8σ。鉴于岩浆池预计具有低反照率，我们发现观测结果最适合用存在大气层来解释。未来测量 TOI-431b 大气层的精确成分并改进熔岩行星大气层模型，将更好地约束熔岩行星的性质与演化。
英文摘要
An open question in exoplanet science is whether rocky exoplanets extremely close in to their host stars, `lava worlds', can retain significant atmospheres. Thermal emission observations via secondary eclipse can be used to determine whether a rocky exoplanet possesses an atmosphere. It is expected that an atmosphere could increase the planet's albedo and/or redistribute heat away from the dayside, reducing the secondary eclipse depth measured. Recent eclipse observations of lava planets, rocky planets hot enough to have liquid magma surfaces, have suggested the presence of atmospheres. Here, we present a single JWST MIRI/LRS partial secondary eclipse of the lava planet TOI-431b. We measure an eclipse depth of 81 $\pm$ 16 ppm, which corresponds to a brightness temperature of $1967^{+237}_{-253}$ K and a brightness temperature ratio R = $0.81\pm0.10$, being 1.2 $σ$ higher than the value reported by Spitzer. The observed brightness temperature ratio is 1.8$σ$ below that of a zero-albedo, zero heat redistribution bare rock (R=1). Given that magma pools are expected to have low albedos, we find that our results are best explained by the presence of an atmosphere. Future work to measure the exact composition of TOI-431b's atmosphere and improve models of lava planet atmospheres would better constrain the nature and evolution of lava planets.
Comments17 pages, 7 figures
