With a new generation of observatories coming online this decade, the process of characterizing exoplanet atmospheres will need to be reinvented. Currently mostly on the instrumental side, characterization bottlenecks will soon appear at the models used to translate spectra into atmospheric properties. Limitations stemming from our stellar and atmospheric models have already been highlighted. Here, we show that the current limitations of the opacity models used to decode exoplanet spectra propagate into an accuracy wall at ~0.5–1.0 dex (that is, three- to tenfold) on the atmospheric properties, which is an order of magnitude above the precision targeted by James Webb Space Telescope Cycle 1 programmes and needed, for example, for meaningful C/O-ratio constraints and biosignature identification. We perform a sensitivity analysis using nine different opacity models and find that most of the retrievals produce harmonious fits owing to compensations in the form of >5σ biases on the derived atmospheric parameters translating into the aforementioned accuracy wall. We suggest a two-tier approach to alleviate this problem, involving a new retrieval procedure and guided improvements in opacity data, their standardization and optimal dissemination.

随着新一代天文台在这十年上线，描述系外行星大气的过程将需要重新发明。目前主要在仪器方面，用于将光谱转换为大气特性的模型很快就会出现表征瓶颈。来自我们的恒星和大气模型的限制已经被强调了。在这里，我们展示了用于解码系外行星光谱的不透明度模型的当前限制传播到大气特性上约 0.5-1.0 dex（即三到十倍）的精度墙，这比詹姆斯韦伯太空望远镜第 1 周期计划所针对的精度，并且需要例如有意义的 C/O 比约束和生物印记识别。σ对导出的大气参数的偏差转化为上述精度墙。我们建议采用两层方法来缓解这个问题，包括新的检索程序和指导改进不透明数据、标准化和最佳传播。