The habitability of stagnant-lid Earths around dwarf stars
The habitability of stagnant-lid Earths around dwarf stars
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矮星周围静止盖地球的宜居性
DOI：
10.1051/0004-6361/201834658
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发表时间：
2019
影响因子：
6.5
通讯作者：
Ruedas
中科院分区：
文献类型：
--
作者：
Godolt;Stracke;Grenfell;Ruedas
背景行星的宜居性取决于多种因素，例如水在其形成过程中的输送、内部和大气的共同演化以及随时间变化的恒星辐射。 目的由于未知数量的岩石系外行星可能在单板对流状态下运行，即没有板块构造，我们的目的是了解处于这种停滞盖状态的行星在什么条件下可能支持宜居的表面条件。了解行星内部和挥发物逸出的相互作用以及主恒星的演化对于确定潜在的宜居性至关重要。 M矮星尤其具有高光度的前主序相，它会因失水而危及周围行星的宜居性。因此，我们探索行星内部二次放气的潜力，以重建水库，从而在后期实现宜居性。方法我们使用一维无云辐射对流气候模型计算 M-、K-、G-和 F-矮星周围的宜居带边界，该模型根据内部演化和不同内部成分和恒星光度演化的放气模型解释了 CO2 和 H2O 的放气历史。宜居带的边缘很大程度上取决于从内部释放的二氧化碳量，而内部边缘主要由恒星辐射决定，一旦足够大的水库被释放。即使在高光度前主序相期间严重失水，只要地幔中保留了一些水，M矮星周围行星的次生表面和大气水库的形成也是可能的。对于浓度在 62 到 125 ppm 之间的小型地幔水库，内部排气的时间延迟允许形成这样的次生水库，特别是对于早中 M 矮星来说，因为它们的前主序寿命比排气时间尺度短。结论我们表明，类地静止盖行星允许在取决于内部成分的连续宜居带内形成宜居的表面条件。在高光度前主序阶段期间，通过重建地表水库严重失水后，来自内部的二次排气可能使M矮星周围的行星具有可居住性。
ContextThe habitability of a planet depends on various factors, such as the delivery of water during its formation, the co-evolution of the interior and the atmosphere, and the stellar irradiation which changes in time.AimsSince an unknown number of rocky extrasolar planets may operate in a one-plate convective regime, i.e. without plate tectonics, our aim is to understand the conditions under which planets in such a stagnant-lid regime may support habitable surface conditions. Understanding the interaction of the planetary interior and outgassing of volatiles in combination with the evolution of the host star is crucial to determining the potential habitability. M-dwarf stars in particular possess a high-luminosity pre-main sequence phase that endangers the habitability of planets around them via water loss. We therefore explore the potential of secondary outgassing from the planetary interior to rebuild a water reservoir allowing for habitability at a later stage.MethodsWe compute the boundaries of the habitable zone around M-, K-, G-, and F-dwarf stars using a 1D cloud-free radiative-convective climate model accounting for the outgassing history of CO2and H2O from an interior evolution and outgassing model for different interior compositions and stellar luminosity evolutions.ResultsThe outer edge of the habitable zone strongly depends on the amount of CO2outgassed from the interior, while the inner edge is mainly determined via the stellar irradiation, as soon as a sufficiently large water reservoir has been outgassed. A build-up of a secondary surface and atmospheric water reservoir for planets around M-dwarf stars is possible even after severe water loss during the high-luminosity pre-main sequence phase as long as some water has been retained within the mantle. For small mantle water reservoirs, between 62 and 125 ppm, a time delay in outgassing from the interior permits such a secondary water reservoir build-up especially for early and mid-M dwarfs because their pre-main sequence lifetimes are shorter than the outgassing timescale.ConclusionsWe show that Earth-like stagnant-lid planets allow for habitable surface conditions within a continuous habitable zone that is dependent on interior composition. Secondary outgassing from the interior may allow for habitability of planets around M-dwarf stars after severe water loss during the high-luminosity pre-main sequence phase by rebuilding a surface water reservoir.
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影响因子：
6.5
作者：
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DOI：
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发表时间：
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通讯作者：
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