1 Institut d'Astrophysique Spatiale (IAS), University of Paris-Saclay, Orsay, France.
2 Institut d'Astrophysique Spatiale (IAS), CNRS, Orsay, France.
Astrobiology. 2019 Jun;19(6):797-810. doi: 10.1089/ast.2018.1938. Epub 2019 Apr 13.
We tested the ability of thermal infrared spectroscopy to retrieve assumed atmospheric compositions for different types of planets orbiting Proxima Centauri and Epsilon Eridani. Six cases are considered, covering a range of atmospheric compositions and some diversity in the bulk composition (rocky, water ocean, hydrogen rich) and the spectral type of the parent star (M and K stars). For some cases, we applied coupled climate chemistry, or climate-only calculations; for other cases, we assumed the atmospheric composition, ground temperature, and surface reflectivity. The IR emission was then calculated from line-by-line radiative transfer models and used to investigate retrieval of input atmospheric species. For the six cases considered, no false positive of the triple bioindicator (HO, CO, and O, in specified conditions) was found. In some cases, results show that the simultaneous acquisition of a visible spectrum would be valuable, for example, when CO is very abundant and its 9.4 μm satellite band hides the 9.6 μm O band in the IR. In each case, determining the mass appears mandatory to identify the planet's nature and have an idea of surface conditions, which are necessary when testing for the presence of life.
我们测试了热红外光谱技术在不同类型围绕半人马座 Proxima 和天苑四 Epsilon Eridani 运行的行星上，对假定大气成分进行反演的能力。考虑了六种情况，涵盖了大气成分的范围以及母体恒星（M 和 K 型恒星）的组成多样性（岩石、水海洋、富氢）和光谱类型。对于某些情况，我们应用了耦合气候化学模型或仅气候模型；对于其他情况，我们假设了大气成分、地面温度和表面反射率。然后，从逐线辐射传输模型计算出红外发射，并用于研究输入大气物种的反演。对于考虑的六种情况，三重生物指标（在特定条件下的 HO、CO 和 O）没有出现错误的阳性结果。在某些情况下，结果表明同时获取可见光谱将非常有价值，例如当 CO 非常丰富且其 9.4 μm 卫星带在红外波段中隐藏了 9.6 μm 的 O 带时。在每种情况下，确定质量似乎都是必需的，以确定行星的性质和表面条件的想法，这对于检测生命存在是必要的。
