English

Vertically resolved magma ocean-protoatmosphere evolution: H$_2$, H$_2$O, CO$_2$, CH$_4$, CO, O$_2$, and N$_2$ as primary absorbers

Earth and Planetary Astrophysics 2021-04-28 v1 Atmospheric and Oceanic Physics Geophysics

Abstract

The earliest atmospheres of rocky planets originate from extensive volatile release during magma ocean epochs that occur during assembly of the planet. These establish the initial distribution of the major volatile elements between different chemical reservoirs that subsequently evolve via geological cycles. Current theoretical techniques are limited in exploring the anticipated range of compositional and thermal scenarios of early planetary evolution, even though these are of prime importance to aid astronomical inferences on the environmental context and geological history of extrasolar planets. Here, we present a coupled numerical framework that links an evolutionary, vertically-resolved model of the planetary silicate mantle with a radiative-convective model of the atmosphere. Using this method we investigate the early evolution of idealized Earth-sized rocky planets with end-member, clear-sky atmospheres dominated by either H2_2, H2_2O, CO2_2, CH4_4, CO, O2_2, or N2_2. We find central metrics of early planetary evolution, such as energy gradient, sequence of mantle solidification, surface pressure, or vertical stratification of the atmosphere, to be intimately controlled by the dominant volatile and outgassing history of the planet. Thermal sequences fall into three general classes with increasing cooling timescale: CO, N2_2, and O2_2 with minimal effect, H2_2O, CO2_2, and CH4_4 with intermediate influence, and H2_2 with several orders of magnitude increase in solidification time and atmosphere vertical stratification. Our numerical experiments exemplify the capabilities of the presented modeling framework and link the interior and atmospheric evolution of rocky exoplanets with multi-wavelength astronomical observations.

Keywords

Cite

@article{arxiv.2101.10991,
  title  = {Vertically resolved magma ocean-protoatmosphere evolution: H$_2$, H$_2$O, CO$_2$, CH$_4$, CO, O$_2$, and N$_2$ as primary absorbers},
  author = {Tim Lichtenberg and Dan J. Bower and Mark Hammond and Ryan Boukrouche and Patrick Sanan and Shang-Min Tsai and Raymond T. Pierrehumbert},
  journal= {arXiv preprint arXiv:2101.10991},
  year   = {2021}
}

Comments

Accepted for publication in JGR Planets; 23 pages, 10 figures; summaries available at https://bit.ly/MO21_blog (blog) and http://bit.ly/MO21_video (video)