法国波尔多大学 Selsis, Franck 的团队报道了一个没有地表岩浆海洋的凉爽失控温室模型。该研究于2023年8月9日发表于国际一流学术期刊《自然》杂志上。

研究人员使用了一致的气候模型，纯蒸汽大气通常由辐射层形成，使它们的热结构强烈依赖于恒星光谱和内部热流。当不施加绝热剖面时，表面较冷；需要比今天高几倍的日照才能融化地壳，这一事件在太阳主序期间不会发生。金星的表面可以在蒸汽大气逃逸之前凝固，这与之前的研究结果相反。在最红的恒星(T_eff<3,000K)周围，无论含水量多少，表面岩浆海洋都无法仅靠恒星作用力形成。

这一发现影响了蒸汽大气和系外行星质量-半径关系的可观测特征，彻底改变了目前对 TRAPPIST-1 行星水含量的限制。与绝热结构不同，辐射对流廓线对不透明度很敏感。因此，对约束较差的高压不透明度的新测量，特别是远离 H₂O 吸收带的测量，蒸汽大气是类地行星演化的重要阶段，对于完善蒸汽大气的模型是有必要的。

人们发现，由撞击或高日照产生的水蒸气大气(其含量相当于地球海洋)会产生表面岩浆海洋。然而，这是假设完全对流结构的结果。

附：英文原文

Title: A cool runaway greenhouse without surface magma ocean

Author: Selsis, Franck, Leconte, Jrmy, Turbet, Martin, Chaverot, Guillaume, Bolmont, meline

Issue&Volume: 2023-08-09

Abstract: Water vapour atmospheres with content equivalent to the Earth’s oceans, resulting from impacts or a high insolation, were found to yield a surface magma ocean. This was, however, a consequence of assuming a fully convective structure. Here, we report using a consistent climate model that pure steam atmospheres are commonly shaped by radiative layers, making their thermal structure strongly dependent on the stellar spectrum and internal heat flow. The surface is cooler when an adiabatic profile is not imposed; melting Earth’s crust requires an insolation several times higher than today, which will not happen during the main sequence of the Sun. Venus’s surface can solidify before the steam atmosphere escapes, which is the opposite of previous works. Around the reddest stars (T_eff<3,000K), surface magma oceans cannot form by stellar forcing alone, whatever the water content. These findings affect observable signatures of steam atmospheres and exoplanet mass–radius relationships, drastically changing current constraints on the water content of TRAPPIST-1 planets. Unlike adiabatic structures, radiative–convective profiles are sensitive to opacities. New measurements of poorly constrained high-pressure opacities, in particular far from the H₂O absorption bands, are thus necessary to refine models of steam atmospheres, which are important stages in terrestrial planet evolution.

DOI: 10.1038/s41586-023-06258-3

Source: https://www.nature.com/articles/s41586-023-06258-3