年轻熔融岩石系外行星通过排气和逃逸的大气演化
Atmospheric evolution through outgassing and escape on young molten rocky exoplanets
浏览论文内容
中文总结 AI 辅助
研究年轻熔融岩石系外行星大气演化，扩展耦合模型并纳入能量限制逃逸模块，探讨多因素对其影响，估计大气损失与成分，揭示大气逃逸、能量传输等对演化的作用及不同条件下的多样演化路径。
中文摘要 AI 辅助
最早的岩石行星大气是由初始挥发性物质存量与大气逃逸之间的竞争塑造的。在年轻的岩浆海洋行星上，排气与大气逃逸相互竞争，控制着挥发性物质的保留和大气演化。我们研究了在岩浆海洋结晶过程中，通过排气进行的大气逃逸和补充如何塑造岩石行星的大气。我们扩展了一个内部-大气耦合模型，通过纳入一个能量限制的大气逃逸模块来模拟岩浆海洋时代的岩石行星演化。比较辐射对流和规定对流大气，我们量化了大气能量传输如何影响逃逸。我们探索了广泛的轨道距离、逃逸效率、氧化态和初始挥发性物质存量，以确定持续的岩浆海洋排气或逃逸占主导的状态。我们估计了类太阳恒星和M矮星周围年轻岩石行星在地质时间尺度上的大气损失和成分。大气逃逸通过削弱温室隔热作用缩短了岩浆海洋的寿命。与纯对流情况相比，辐射对流大气减少了凝固时间尺度。挥发性物质溶解到岩浆海洋中与逃逸相互作用，随着时间的推移通过保留更多可溶物种来化学分离行星挥发性物质预算。对于地球质量的行星，如果损失率保持适中，大气就能存活。地幔氧化还原状态仍然是保留大气成分的关键控制因素：高氧逸度（fO2）产生较重的、富含H2O和CO2的大气，而低fO2产生轻的、以H2或CO为主的大气，这与之前的研究一致。轨道距离、初始挥发性物质存量和恒星类型产生了从裸露岩石行星到拥有浓厚大气的岩浆海洋的多样演化路径，大气成分从H2主导到SO2主导。
英文摘要
The earliest rocky planet atmospheres are shaped by competition between initial volatile inventories and atmospheric escape. On young magma ocean planets, outgassing competes with atmospheric escape, controlling volatile retention and atmospheric evolution. We investigate how atmospheric escape and replenishment via outgassing during magma ocean crystallization shape rocky planet atmospheres. We extend a coupled interior-atmosphere model to simulate rocky planet evolution during the magma ocean era by incorporating an energy-limited atmospheric escape module. Comparing radiative-convective and prescribed-convective atmospheres, we quantify how atmospheric energy transport affects escape. We explore a wide range of orbital separations, escape efficiencies, oxidation states, and initial volatile inventories to identify regimes where sustained magma-ocean outgassing or escape dominates. We estimate atmospheric loss and compositions for young rocky planets around Sun-like and M-dwarf stars over geologic timescales. Atmospheric escape shortens magma ocean lifetimes by weakening greenhouse insulation. Radiative-convective atmospheres reduce solidification timescales compared to purely convective cases. Volatile dissolution into the magma ocean interacts with escape to chemically fractionate the planetary volatile budget over time by retaining more soluble species. For Earth-mass planets, atmospheres survive if loss rates remain moderate. Mantle redox state remains a key control on retained atmospheric composition: high oxygen fugacity (fO2) yields heavier, H2O- and CO2-rich atmospheres, while low fO2 produces light, H2- or CO-dominated atmospheres, consistent with previous studies. Orbital separation, initial volatile inventory, and stellar type produce diverse evolutionary pathways, from bare rocky planets to magma oceans with thick atmospheres, ranging from H2- to SO2-dominated.
