About The Loss Of A Primordial Atmosphere Of Super-Earths By Planetesimal Impacts
We consider planets composed of water ice and rock, located far from a central star. In an earlier study, computing the growth of planets by continuous accretion, we found that a large fraction of the ice evaporates upon accretion, creating a water vapor atmosphere.
Here we consider accretion as a discrete series of planetesimal impacts (of order 108), at the same time-dependent accretion rate, and investigate the fate of the vapor, as a result of its interaction with the accreting planetesimals. We find that a large fraction of the vapor escapes.
The remaining fraction may form an outer layer of ice after the termination of accretion and cooling of the surface. The escaped water mass may significantly alter the ice-to-rock ratio of the planet. We investigate the effect of different choices of parameters such as the ice-to-rock ratio, the planetesimal size distribution, and the impact velocities.
We find that the planetesimal size distribution has a negligible effect and explain why. By contrast, the ice-to-rock ratio and impact velocities affect the fraction of retained water masses considerably.
Michael Lozovsky, Dina Prialnik, Morris Podolak
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2302.05921 [astro-ph.EP] (or arXiv:2302.05921v1 [astro-ph.EP] for this version)
Related DOI:
https://doi.org/10.1093/mnrasl/slad019
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Submission history
From: Michael Lozovsky
[v1] Sun, 12 Feb 2023 14:23:04 UTC (556 KB)
https://arxiv.org/abs/2302.05921
Astrobiology
