Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, Japan.
Space Science Institute, Boulder, Co, USA.
Sci Rep. 2020 May 4;10(1):7432. doi: 10.1038/s41598-020-64436-z.
To find potentially habitable exoplanets, space missions employ the habitable zone (HZ), which is the region around a star (or multiple stars) where standing bodies of water could exist on the surface of a rocky planet. Follow-up atmospheric characterization could yield biosignatures signifying life. Although most iterations of the HZ are agnostic regarding the nature of such life, a recent study argues that a complex life HZ would be considerably smaller than that used in classical definitions. Here, I use an advanced energy balance model to show that such an HZ would be considerably wider than originally predicted given revised CO limits and (for the first time) N respiration limits for complex life. The width of this complex life HZ (CLHZ) increases by ~35% from ~0.95-1.2 AU to 0.95-1.31 AU in our solar system. Similar extensions are shown for stars with stellar effective temperatures between 2,600-9,000 K. I define this CLHZ using lipid solubility theory, diving data, and results from animal laboratory experiments. I also discuss implications for biosignatures and technosignatures. Finally, I discuss the applicability of the CLHZ and other HZ variants to the search for both simple and complex life.
为了寻找潜在宜居的系外行星，太空任务采用了宜居带（HZ），这是恒星（或多颗恒星）周围的区域，在那里，岩石行星表面可能存在稳定的水体。后续的大气特征分析可能会产生表明生命存在的生物特征。尽管 HZ 的大多数迭代都不考虑这种生命的性质，但最近的一项研究认为，复杂生命的 HZ 会比经典定义中使用的 HZ 小得多。在这里，我使用先进的能量平衡模型表明，在修订后的 CO 限制（首次）和复杂生命的 N 呼吸限制下，这种 HZ 会比最初预测的要宽得多。在我们的太阳系中，这种复杂生命 HZ（CLHZ）的宽度从 0.95-1.2 AU 增加到 0.95-1.31 AU，增加了约 35%。对于恒星有效温度在 2600-9000 K 之间的恒星，也显示了类似的扩展。我使用脂溶性理论、潜水数据和动物实验室实验的结果来定义这个 CLHZ。我还讨论了对生物特征和技术特征的影响。最后，我讨论了 CLHZ 和其他 HZ 变体在寻找简单生命和复杂生命中的适用性。
