![Figure showing the structure of pure carbon planets ranging from 0.1 to 20 Earth masses with a surface temperature of 300K. Color bar indicates density in g/cm3 . -- [astro-ph.EP]](https://i0.wp.com/astrobiology.com/wp-content/uploads/2026/09/Modeling-Carbon.png?fit=1200%2C675&ssl=1)
[astro-ph.EP] A planet’s interior structure not only influences its habitability, but it also provides information about the planet’s formation and history.
In the quest to characterize the variety of planetary discoveries, the most common practice is to rely on our understanding of the Earth’s differentiated interior structure, with an iron core and silicate mantle as a starting point.
However, recent work by arXiv:2408.07761 [astro-ph.EP] shows that these assumptions may not be true for all planetary systems as the composition of the condensed material can change drastically towards a carbon mantle instead of a silicate one, once the C/O ratio of the system approaches and exceeds approximately 0.9.
In an effort to more fully understand the range of possible planetary bodies, we added the ability to model carbon-based mantles to our open-source planetary interior solver, MAGRATHEA. The newly added carbon mantle includes three relevant allotropes of carbon: graphite, diamond, and BC8 (body centered cubic with eight atoms per cell).
Robert Royer III, David R. Rice, Jason H. Steffen
Comments: Published in the Open Journal of Astrophysics
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2608.27892 [astro-ph.EP] (or arXiv:2608.27892v1 [astro-ph.EP] for this version)
https://doi.org/10.48550/arXiv.2608.27892
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Submission history
From: Robert Royer Iii
[v1] Fri, 28 Aug 2026 03:57:08 UTC (1,218 KB)
https://arxiv.org/abs/2608.27892
Astrobiology
