发表机构
University of Texas, Austin; Massachusetts Institute of Technology; Leibniz Institute for Astrophysics Potsdam; University of Amsterdam; The Open University of Israel; Arizona State University; University of California, Santa Cruz; Carnegie Institution for Science（德克萨斯大学奥斯汀分校; 麻省理工学院; 波茨坦莱布尼茨天体物理研究所; 阿姆斯特丹大学; 以色列开放大学; 亚利桑那州立大学; 加州大学圣克鲁兹分校; 卡内基科学学会）
机构由 AI 辅助整理，请以论文原文为准。AI 中文总结
本研究探讨温暖凌星海王星及亚海王星行星高推断内部温度的三种可能原因，发现潮汐加热和硅酸盐雨出不太可能，而云凝结可降低温度但仍高于预测，未来需结合热辐射和甲烷丰度测量以区分。
AI 中文摘要
利用JWST对一颗温暖的、年龄为10-30百万年的亚海王星前身星（V1298 Tau b）和一颗年龄约为3.4十亿年的温暖超级海王星（WASP-107b）进行的大气表征，揭示了极低的甲烷丰度。大气前向模型发现，推断的内部温度（450 K和500 K）高于预期，这与假设对流内部的行星形成和核-包层演化预测（分别为70 K和150 K）不一致。我们探索了三种假设来调和高内部温度与演化模型之间的矛盾：潮汐加热、硅酸盐雨出以及由于深层云凝结导致的热捕获。对于V1298 Tau b，潮汐加热需要高行星倾角（≥70°）和低降低的潮汐品质因子（约100），这意味着极短的倾角阻尼时间尺度（<10^4年）。尽管高倾角可以通过自旋-轨道共振锁定来维持，但这需要精细调节，因此不太可能。硅酸盐雨出可以将年轻的V1298 Tau b深层大气（0.1-1 bar）的温度提高约700 K，而无需极高的内部温度，但不太可能解释WASP-107b，因为硅酸盐雨出的时间尺度预计远短于其年龄。在自洽大气模型中包含云凝结，将V1298 Tau b的推断内部温度从500 K降至300 K，但仍超过核-包层预测（150 K）。未来对年轻凌星行星（如V1298 Tau b）的热辐射测量，结合甲烷丰度随年龄的变化，将有助于区分这些情景。
英文摘要
Atmospheric characterization of a warm 10-30 Myr old sub-Neptune progenitor (V1298 Tau b) and a $\sim$3.4 Gyr old warm super-Neptune (WASP-107b) using JWST have revealed extremely low methane abundance. Atmospheric forward models find higher than expected inferred intrinsic temperatures (450~K and 500~K) --- inconsistent with theoretical planet formation and core-envelope evolution predictions (70K and 150K respectively) assuming a convective interior. We explore three hypotheses to reconcile the high intrinsic temperatures with evolutionary models --- tidal heating, silicate rainout and heat trapping due to deep cloud condensation. Tidal heating requires high planetary obliquity ($\gtrsim70^{\circ}$) and low reduced tidal quality factor ($\sim$100) for V1298 Tau b, implying an extremely short obliquity damping timescale ($<$10$^{4}$ years). Although high obliquity may be maintained by spin--orbit resonant locking, it requires fine-tuning and is therefore unlikely. Silicate rainout can increase the temperature in the deep atmosphere of the young V1298 Tau b (0.1-1 bar) by $\sim$700K, without requiring extremely high intrinsic temperature, but is unlikely to explain WASP-107b, as silicate rainout timescales are expected to be much shorter than its age. Including cloud condensation in self-consistent atmospheric models reduces the inferred intrinsic temperature for V1298 Tau b from 500K to 300K, still exceeding the core-envelope prediction (150K). Future measurements of thermal emission from young transiting planets such as V1298 Tau b, combined with methane abundances as a function of age, will be needed to distinguish between these scenarios.
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