arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 2009.14599astro-ph.EPphysics.ao-phphysics.geo-ph
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地幔氧化态和逃逸对地球岩浆海洋大气演化的影响

Effect of mantle oxidation state and escape upon the evolution of Earth's magma ocean atmosphere

Nisha Katyal, Gianluigi Ortenzi, John Lee Grenfell, Lena Noack, Frank Sohl, Mareike Godolt, Antonio García Muñoz, Franz Schreier, Fabian Wunderlich, Heike Rauer

摘要:

岩浆海洋时期是决定地球大气如何发展成可居住环境的关键阶段。然而,在决定早期地球大气层的关键过程中,例如行星内部的放气和物种逃逸到太空中,存在着重大的不确定性。本文研究了不同地幔氧化还原状态下不同物质的释气和H $_2$的逃逸对岩浆海洋期大气组成和演化的影响。我们包括一个重要的新的大气-内部耦合机制,即地幔的氧化还原演化强烈影响的物种的放气。我们模拟的挥发性放气和化学形态在表面的各种氧化还原状态的地幔采用C-H-O为基础的化学形态模型结合内部放气模型。然后,我们应用逐行辐射转移模型来研究行星的红外发射和传输方面的远程外观。最后,我们使用一个参数化的扩散限制和XUV能量驱动的大气逃逸模型来计算H $_2$到空间的损失。我们模拟了地球岩浆海洋时期还原或氧化大气的热发射和透射光谱。与富含H $_2$ O和CO $_2$的氧化或厚大气相比,由H $_2$组成的还原或薄大气向空间发射更多的辐射,并且具有更大的有效高度。我们得到的H2从地幔到大气中的释气速率是扩散限制逃逸到空间的速率的10倍。我们的工作提供了有用的洞察地球大气在岩浆海洋时期的发展,以及输入,以指导未来的研究讨论系外行星内部成分。

英文摘要:

The magma ocean period was a critical phase determining how Earth atmosphere developed into habitability. However there are major uncertainties in the role of key processes such as outgassing from the planetary interior and escape of species to space that play a major role in determining the atmosphere of early Earth. We investigate the influence of outgassing of various species and escape of H$_2$ for different mantle redox states upon the composition and evolution of the atmosphere for the magma ocean period. We include an important new atmosphere-interior coupling mechanism namely the redox evolution of the mantle which strongly affects the outgassing of species. We simulate the volatile outgassing and chemical speciation at the surface for various redox states of the mantle by employing a C-H-O based chemical speciation model combined with an interior outgassing model. We then apply a line-by-line radiative transfer model to study the remote appearance of the planet in terms of the infrared emission and transmission. Finally, we use a parameterized diffusion-limited and XUV energy-driven atmospheric escape model to calculate the loss of H$_2$ to space. We have simulated the thermal emission and transmission spectra for reduced or oxidized atmospheres present during the magma ocean period of Earth. Reduced or thin atmospheres consisting of H$_2$ in abundance emit more radiation to space and have larger effective height as compared to oxidized or thick atmospheres which are abundant in H$_2$O and CO$_2$. We obtain the outgassing rates of H2 from the mantle into the atmosphere to be a factor of ten times larger than the rates of diffusion-limited escape to space. Our work presents useful insight into the development of Earth atmosphere during the magma ocean period as well as input to guide future studies discussing exoplanetary interior compositions.

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