Detailed chemical compositions of host stars of planets: II. Exploration of the interior of Earth-like exoplanets

Ternary diagrams showing estimated mantle compositions of major mineral oxides (normalized by SiO2 + MgO + FeO = 100 wt%) for the model exo-Earth sample (for clarity, the sample is arbitrarily split into two groups). The range of squares indicates the 1 ???? modeled. uncertainties in the normalized mantle compositions of individual planets. The normalized compositions of SiO2, MgO and FeO of the Earth’s mantle (McDonough & Sun 1995) and the Martian mantle (Yoshizaki & McDonough 2020) are presented for reference.

A major goal in the discovery and characterization of exoplanets is to identify Earth-like worlds that are similar to (or otherwise distinct from) our Earth.

Recent results have highlighted the importance of applying devolatilization – i.e. depletion of volatile compounds – to the chemical composition of host stars of planets to constrain the global composition and interiors of exoplanets from terrestrial type. In this work, we apply such an approach to a selected sample of 13 solar-like planet-hosting stars, for which high-precision photospheric abundances were determined in the first paper of the series. With the resulting devolatilized stellar composition (i.e. the overall planetary composition of the model) along with other constraints, including mass and radius, we model the detailed mineralogy and interior structure of hypothetical terrestrial planets of the habitable zone (“exo-Earths”) around these stars.

The model output shows that most of these exo-Earths should have a broadly Earth-like composition and interior structure, consistent with conclusions drawn independently from analysis of polluted white dwarfs. The exceptions are exo-Earths Kepler-10 and Kepler-37, which we believe are heavily oxidized and would therefore develop much smaller metal cores than Earth. The study of our model of devolatilization at its extremes as well as the variation of planetary mass and radius (within the terrestrial regime) reveals potential diversities within the telluric planets.

By considering (i) high-precision stellar abundances, (ii) devolatilization, and (iii) planetary mass and radius holistically, this work represents essential steps to explore the detailed mineralogy and interior structure of planet-like exoplanets. terrestrial, which in turn are fundamental to our understanding of planetary dynamics and long-term evolution.

Haiyang S. Wang, Sascha P. Quanz, David Yong, Fan Liu, Fabian Seidler, Lorena Acuña, Stephen J. Mojzsis

Comments: Accepted for publication in MNRAS; 19 pages, 14 figures, 2 tables; a related conference is available at this URL https
Subjects: Terrestrial and planetary astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Cite as: arXiv:2204.09558 [astro-ph.EP] (or arXiv:2204.09558v1 [astro-ph.EP] for this release)
Submission History
From: Haiyang Wang
[v1] Wed Apr 20 2022 3:52:47 PM UTC (6,494 KB)

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