Like the planets and moons in our solar system, the surfaces of terrestrial exoplanets may be shaped by volcanic activity. The magnitudes and rates of volcanic activity on terrestrial exoplanets will be intimately linked to their sizes and internal heating rates and can either facilitate or preclude the existence of habitable environments. In order to place bounds on the potential for such activity, we estimate total internal heating rates for 53 exoplanets with masses and radii up to ∼8M⊕ and 2R⊕, respectively, assuming that internal heating is drawn from both radiogenic and tidal sources. We then compare these internal heating rates to those of the planets and moons in our solar system in an attempt to constrain the expected rates of volcanic activity on these extrasolar worlds. We find that all 53 of the exoplanets surveyed are likely to have volcanic activity at their surfaces, and that at least 26% of these planets may be extrasolar ocean worlds. The majority of these ocean worlds may be similar in structure to the icy moons of the giant planets, having internal oceans beneath layers of surface ice. If so, these planets may exhibit cryovolcanism (i.e., icy volcanism) at their surfaces. Recent studies have shown that extrasolar volcanism could be detected by high-resolution spectrographs on existing ground-based telescopes. In the case of planets with densities and/or effective temperatures that are consistent with H2O-rich compositions, spectral identification of excess water vapor and other molecules that are explosively vented into space during cryovolcanic eruptions could serve as a way to infer the presence of subsurface oceans, and therefore indirectly assess their habitability. Considering the implications for habitability, our results suggest that continued characterization of terrestrial exoplanets in terms of their potential for volcanic activity should be a priority in the coming years.

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类地系外行星火山活动的预测速率以及对太阳系外海洋世界冰火山活动的影响

就像我们太阳系中的行星和卫星一样，类地系外行星的表面可能是由火山活动形成的。类地系外行星上火山活动的幅度和速率将与其大小和内部加热速率密切相关，并且可以促进或排除宜居环境的存在。为了限制这种活动的可能性，我们估计了 53 颗质量和半径分别高达 ~8M⊕ 和 2R⊕ 的系外行星的总内部加热速率，假设内部加热来自放射源和潮汐源。然后，我们将这些内部加热速率与太阳系中行星和卫星的内部加热速率进行比较，以试图限制这些太阳系外世界火山活动的预期速率。我们发现所有被调查的 53 颗系外行星的表面都可能有火山活动，并且这些行星中至少有 26% 可能是太阳系外的海洋世界。这些海洋世界中的大多数可能在结构上类似于巨行星的冰卫星，在表面冰层下有内部海洋。如果是这样，这些行星可能会在其表面表现出低温火山活动（即冰火山活动）。最近的研究表明，可以通过现有地面望远镜的高分辨率光谱仪检测到太阳系外火山活动。如果行星的密度和/或有效温度与富含 H2O 的成分一致，对在冰火山喷发期间爆炸性地排放到太空中的过量水蒸气和其他分子进行光谱识别，可以作为推断地下海洋存在的一种方式，从而间接评估它们的宜居性。考虑到对宜居性的影响，我们的研究结果表明，在未来几年，继续对类地系外行星进行火山活动潜力的表征应该是优先事项。