Atmospheric Seasonality as an Exoplanet Biosignature
Atmospheric Seasonality as an Exoplanet Biosignature
复制标题
大气季节性作为系外行星的生物特征
DOI：
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发表时间：
2018
期刊：
影响因子：
--
通讯作者：
T. Lyons
中科院分区：
文献类型：
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作者：
S. Olson;E. Schwieterman;C. Reinhard;A. Ridgwell;S. Kane;V. Meadows;T. Lyons
目前对系外行星生物特征的研究主要集中在生命的静态证据上，例如O2或CH 4等生物气体的存在。然而，预期的类地行星大气的多样性和传统生物特征的“假阳性”和“假阴性”的可能性促使探索额外的生命探测策略，包括随时间变化的信号。大气成分的季节性变化是地球上的一种生物调制现象，也可能发生在其他地方，因为它是生物圈和随时间变化的日照之间相互作用的自然结果。寻找季节性作为生物特征将避免许多关于特定代谢的假设，并提供一个直接量化生物通量的机会，使我们能够描述，而不是简单地识别，系外行星上的生物圈。尽管有这种潜力，但还没有全面的研究季节性作为系外行星的生物特征。在这里，我们提供了一个基础，进一步的研究，通过审查生物和非生物控制的幅度和可检测性的大气CO2，CH 4，O2，和O3在地球上的季节性。我们还考虑了一个有人居住的世界的例子，其中大气的季节性可能是其生物圈最显着的表现。我们表明，生活在一个低O2的行星，如弱含氧的中元古代地球可以指纹O3的季节性变化，揭示在其UV哈特利-哈金斯带。这个例子强调了未来直接成像望远镜任务对紫外能力的需求（例如，LUVOIR/HabEx），并说明了研究时间生物特征对系外行星生命探测/表征的诊断重要性。
Current investigations of exoplanet biosignatures have focused on static evidence of life, such as the presence of biogenic gases like O2 or CH4. However, the expected diversity of terrestrial planet atmospheres and the likelihood of both “false positives” and “false negatives” for conventional biosignatures motivate exploration of additional life detection strategies, including time-varying signals. Seasonal variation in atmospheric composition is a biologically modulated phenomenon on Earth that may occur elsewhere because it arises naturally from the interplay between the biosphere and time-variable insolation. The search for seasonality as a biosignature would avoid many assumptions about specific metabolisms and provide an opportunity to directly quantify biological fluxes—allowing us to characterize, rather than simply recognize, biospheres on exoplanets. Despite this potential, there have been no comprehensive studies of seasonality as an exoplanet biosignature. Here, we provide a foundation for further studies by reviewing both biological and abiological controls on the magnitude and detectability of seasonality of atmospheric CO2, CH4, O2, and O3 on Earth. We also consider an example of an inhabited world for which atmospheric seasonality may be the most notable expression of its biosphere. We show that life on a low O2 planet like the weakly oxygenated mid-Proterozoic Earth could be fingerprinted by seasonal variation in O3 as revealed in its UV Hartley–Huggins bands. This example highlights the need for UV capabilities in future direct-imaging telescope missions (e.g., LUVOIR/HabEx) and illustrates the diagnostic importance of studying temporal biosignatures for exoplanet life detection/characterization.
太阳系外行星和虚假的大气生物特征：微流星体的作用
影响因子：
2.4
作者：
Court R
通讯作者：
Court R