Université Paris-Saclay, UVSQ, CNRS, LATMOS, Guyancourt, France.
Normandie Univ, COBRA UMR 6014 et FR 3038 Univ Rouen; INSA Rouen; CNRS IRCOF, Mont-Saint-Aignan, France.
Astrobiology. 2023 Jun;23(6):723-732. doi: 10.1089/ast.2022.0021.
Photochemical hazes are expected to form and significantly contribute to the chemical and radiative balance of exoplanets with relatively moderate temperatures, possibly in the habitable zone of their host star. In the presence of humidity, haze particles might thus serve as cloud condensation nuclei and trigger the formation of water droplets. In the present work, we are interested in the chemical impact of such a close interaction between photochemical hazes and humidity on the organic content composing the hazes and on the capacity to generate organic molecules with high prebiotic potential. For this purpose, we explore experimentally the sweet spot by combining N-dominated super-Earth exoplanets in agreement with Titan's rich organic photochemistry and humid conditions expected for exoplanets in habitable zones. A logarithmic increase with time is observed for the relative abundance of oxygenated species, with O-containing molecules dominating after 1 month only. The rapidity of the process suggests that the humid evolution of N-rich organic haze provides an efficient source of molecules with high prebiotic potential.
光化学烟雾预计会在温度适中的系外行星（其宿主恒星的宜居带内）中形成，并对其化学和辐射平衡产生重大影响。在湿度存在的情况下，烟雾颗粒可能充当云凝结核并引发水滴的形成。在本工作中，我们关注的是光化学烟雾与湿度之间这种紧密相互作用对构成烟雾的有机物质的化学影响，以及生成具有高原始生物潜力的有机分子的能力。为此，我们通过将与泰坦丰富的有机光化学性质一致的 N 占主导地位的超级地球系外行星与宜居带中系外行星预期的潮湿条件相结合，从实验上探索了这一“甜蜜点”。含氧物种的相对丰度随时间呈对数增加，只有在 1 个月后才以含 O 的分子为主。这一过程的迅速性表明，富含 N 的有机烟雾的潮湿演化提供了具有高原始生物潜力的分子的有效来源。
