耦合光化学-气候模型研究TRAPPIST-1行星上可能的稀薄大气
Coupled Photochemical-Climate Modeling of Plausible Tenuous Outgassed Atmospheres on the TRAPPIST-1 Planets
AI总结：
本文通过耦合光化学-气候模型，研究TRAPPIST-1行星上稀薄大气的可能性，发现其大气压力范围在10^-4至1巴之间，部分行星可能存在适宜生命存在的环境。
摘要：
可用JWST观测数据表明，TRAPPIST-1系统中的几颗行星可能缺乏大气或拥有非常稀薄的大气。然而，这些行星预期的高大气逃逸率表明，任何稀薄的大气必须通过持续的出气来补充，而以往的研究未广泛考虑表面压力低于1巴的情况。本文展示，TRAPPIST-1行星上的稀薄大气可能成立，支持了恒定的水和/或二氧化碳出气率与假设的高逃逸率（高达~10^30 s^-1）的平衡。我们使用耦合的光化学-气候模型，并从广泛的出气、表面沉积和大气顶层逃逸率相空间中采样，测试每颗行星数百种大气。关键的是，我们的模型还允许表面压力根据源和汇的平衡变化。我们发现，通过水和/或二氧化碳出气，生成了6种不同的组成原型，大气通常介于10^-4至1巴之间。我们发现，TRAPPIST-1d和e的潜在宜居表面环境可能在0.05至2巴和0.5至1巴之间。在可能的情况下，我们比较了我们的模型与JWST观测数据，对于TRAPPIST-1b、c、d和e，所有发现的大气匹配可用传输数据至<3σ。然而，发射数据与限制在稀薄O₂主导组成下的大气结果一致，对于TRAPPIST-1b（<0.01巴）和c（<0.2巴），可能含有痕量SO₂。
英文摘要：
Available JWST observations TRAPPIST-1 system have suggested that several of the planets are likely airless, or possess a very tenuous atmosphere. However, the high atmospheric escape rates expected for these planets suggest that any tenuous atmosphere must be replenished by constant outgassing, and past studies on modeling potential atmospheres for the planets have not widely considered surface pressures <1 bar. Here, we show that tenuous atmospheres on the TRAPPIST-1 planets are likely possible, supported by constant plausible rates of water and/or CO$_{2}$ outgassing against assumed high escape rates (up to ~10$^{30}$ s$^{-1}$). We use a coupled photochemical-climate model and sample from a broad phase space of outgassing, surface deposition, and top-of-atmosphere escape rates to test hundreds of atmospheres per planet. Critically, our model also allows surface pressure to vary based on the balance of sources and sinks. We find that 6 different compositional archetypes are generated via H$_{2}$O and/or CO$_{2}$ outgassing across our phase space, and atmospheres commonly fall between 10$^{-4}$ -- 1 bar. We find that potentially habitable surface environments are possible for TRAPPIST-1d and e at pressures between 0.05 -- 2 bar and 0.5 -- 1 bar, respectively. Where possible, we compare our models to JWST observational data for TRAPPIST-1b, c, d, and e; all atmospheres found in this study for these planets match available transmission data to <3$σ$. However, emission data are consistent with atmospheric outcomes constrained to thin O$_{2}$-dominated compositions for TRAPPIST-1b ($\lesssim$0.01 bars) and c ($\lesssim$0.2 bars), which may or may not contain trace SO$_{2}$.
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