A number of transiting, potentially habitable Earth-sized exoplanets have recently been detected around several nearby M dwarf stars. These worlds represent important targets for atmospheric characterization for the upcoming NASA James Webb Space Telescope (JWST). Given that available time for exoplanet characterization will be limited, it is critically important to first understand the capabilities and limitations of JWST when attempting to detect atmospheric constituents for potentially Earth-like worlds orbiting cool stars. Here, we explore coupled climate-chemistry atmospheric models for Earth-like planets orbiting a grid of M dwarf hosts. Using a newly-developed and validated JWST instrument model—the JWST Exoplanet Transit Simulator—we investigate the detectability of key biosignature and habitability indicator gaseous species for a variety of relevant instruments and observing modes. Spectrally resolved detection scenarios as well as cases where the spectral impact of a given species is integrated across the entire range of an instrument/mode are considered and serve to highlight the importance of considering information gained over an entire observable spectral range. Our results indicate that detectability of gases at individual wavelengths is overly challenging for JWST but integrating the spectral impact of a species across the entire wavelength range of an instrument/mode significantly improves requisite detection times. When considering the entire spectral coverage of an instrument/mode, detections of methane, carbon dioxide, oxygen and water at signal-to-noise ratio 5 could be achieved with observations of several tens of transits (or less) for cloud-free Earth-like worlds orbiting mid- to late-type M dwarfs at system distances of up to 10–15 pc. When compared to previous results, requisite exposure times for gas species detection depend on approaches to quantifying the spectral impact of the species as well as underlying photochemical model assumptions. Thus, constraints on atmospheric abundances, even if just upper limits, by JWST have the potential to further our understanding of terrestrial atmospheric chemistry.

最近在附近的几颗 M 矮星周围发现了许多过境的、可能适合居住的地球大小的系外行星。这些世界代表了即将到来的 NASA 詹姆斯韦伯太空望远镜 (JWST) 大气特征描述的重要目标。鉴于用于系外行星表征的可用时间将是有限的，因此在尝试探测围绕冷恒星运行的潜在类地世界的大气成分时，首先了解 JWST 的能力和局限性至关重要。在这里，我们探索了类地行星的耦合气候-化学大气模型，这些行星围绕 M 矮宿主的网格运行。使用新开发和验证的 JWST 仪器模型——JWST 系外行星凌日模拟器——我们研究了各种相关仪器和观测模式的关键生物特征和宜居性指示气体物种的可检测性。光谱解析的检测场景以及给定物种的光谱影响在仪器/模式的整个范围内整合的情况都被考虑在内，并有助于强调考虑在整个可观察光谱范围内获得的信息的重要性。我们的结果表明，单个波长的气体的可检测性对于 JWST 来说极具挑战性，但在仪器/模式的整个波长范围内整合物种的光谱影响显着缩短了必要的检测时间。当考虑仪器/模式的整个光谱覆盖范围时，通过对无云地球的几十次（或更少）凌日的观测，可以实现对甲烷、二氧化碳、氧气和水的信噪比为 5 的检测。就像在系统距离高达 10-15 pc 的情况下围绕中晚期 M 矮星运行的世界。与之前的结果相比，气体物种检测所需的暴露时间取决于量化物种光谱影响的方法以及潜在的光化学模型假设。因此，JWST 对大气丰度的限制，即使只是上限，也有可能进一步加深我们对陆地大气化学的理解。通过对在系统距离高达 10– 的中晚期 M 矮星运行的无云类地球世界进行数十次凌日（或更少）的观测，可以实现信噪比为 5 的氧气和水。 15 个。与之前的结果相比，气体物种检测所需的暴露时间取决于量化物种光谱影响的方法以及潜在的光化学模型假设。因此，JWST 对大气丰度的限制，即使只是上限，也有可能进一步加深我们对陆地大气化学的理解。通过对在系统距离高达 10– 的中晚期 M 矮星运行的无云类地球世界进行数十次凌日（或更少）的观测，可以实现信噪比为 5 的氧气和水。 15 个。与之前的结果相比，气体物种检测所需的暴露时间取决于量化物种光谱影响的方法以及潜在的光化学模型假设。因此，JWST 对大气丰度的限制，即使只是上限，也有可能进一步加深我们对陆地大气化学的理解。气体物种检测所需的暴露时间取决于量化物种光谱影响的方法以及潜在的光化学模型假设。因此，JWST 对大气丰度的限制，即使只是上限，也有可能进一步加深我们对陆地大气化学的理解。气体物种检测所需的暴露时间取决于量化物种光谱影响的方法以及潜在的光化学模型假设。因此，JWST 对大气丰度的限制，即使只是上限，也有可能进一步加深我们对陆地大气化学的理解。