Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA.
Center for Radioastronomy and Astrophysics Mackenzie, Sao Paulo, Brazil.
Astrobiology. 2020 Dec;20(12):1465-1475. doi: 10.1089/ast.2019.2126.
The discovery of potentially habitable planets around the ultracool dwarf star Trappist-1 naturally poses the question: could Trappist-1 planets be home to life? These planets orbit very close to the host star and are most susceptible to the UV radiation emitted by the intense and frequent flares of Trappist-1. Here, we calculate the UV spectra (100-450 nm) of a superflare observed on Trappist-1 with the K2 mission. We couple radiative transfer models to this spectra to estimate the UV surface flux on planets in the habitable zone of Trappist-1 (planets and ), assuming atmospheric scenarios based on a prebiotic and an oxygenic atmosphere. We quantify the impact of the UV radiation on living organisms on the surface and on a hypothetical planet ocean. Finally, we find that for non-oxygenic planets, UV-resistant life-forms would survive on the surface of planets f and g. Nevertheless, more fragile organisms () could be protected from the hazardous UV effects at ocean depths greater than 8 m. If the planets have an ozone layer, any life-forms studied here would survive in the habitable zone planets.
围绕 ultracool 矮星 Trappist-1 发现潜在宜居行星自然提出了一个问题：Trappist-1 行星是否可能存在生命？这些行星非常靠近宿主恒星，因此最容易受到 Trappist-1 强烈且频繁耀斑发出的 UV 辐射的影响。在这里，我们使用 K2 任务计算了 Trappist-1 上一次超耀斑的 UV 光谱（100-450nm）。我们将辐射传输模型与该光谱相结合，根据基于前生物和含氧大气的大气情景，估算了 Trappist-1 宜居带中行星（行星 和 ）上的 UV 表面通量。我们量化了 UV 辐射对表面和假设行星海洋中生命的影响。最后，我们发现对于非含氧行星，抗 UV 的生命形式将在行星 f 和 g 的表面存活。然而，更脆弱的生物体（）可以在海洋深处超过 8m 处免受危险的 UV 影响。如果行星有臭氧层，这里研究的任何生命形式都将在宜居带行星中存活。
