Stellar Abundances as Probes of Rocky Exoplanet Interiors: The Mantle Composition and Mineralogy of GJ 486b
6 affiliations
- 1National Institute of Science Education and Research
- 2Homi Bhabha National Institute
- 3Indian Institute of Science Education and Research (IISER) Mohali
- 4Indian Institute of Science Education and Research
- 5Indian Institute of Technology
- 6Pennsylvania State University
Abstract
Over the past three decades, hundreds of rocky exoplanets have been discovered. Some of these show atmospheric signatures indicative of diverse chemical compositions. Interpreting these atmospheres requires a physically grounded understanding of planetary interiors, as interior composition and mineralogy govern the formation and evolution of secondary atmospheres. Rocky terrestrial exoplanets are expected to inherit the refractory composition of their host stars, providing a direct pathway to constrain their bulk composition and mineralogy. However, a large fraction of these planets orbit M-type stars, whose compositions remain poorly constrained because of limited and uncertain stellar abundance measurements. Here, we present a physically consistent framework that connects stellar abundances to the interior structure and mineralogy of rocky exoplanets by combining stellar abundance inference, devolatilization modeling to estimate bulk and mantle elemental abundances, interior structure calculations to derive pressure–temperature ( P – T ) profiles, and thermodynamic equilibrium modeling of mantle mineralogy. We first benchmark the framework against Earth and then apply it to the super-Earth GJ 486b using chemically consistent abundances derived from ensembles of similar M-dwarf hosts. We find that GJ 486b likely hosts an iron-rich and silica-poor mantle relative to Earth while preserving the major mantle phase transitions. Sensitivity analyses show that the overall mineralogical structure is robust to variations in bulk composition and P – T profiles, with temperature primarily modulating phase proportions near key transitions. Our results demonstrate that stellar chemical abundances, when combined with physically motivated devolatilization models, provide robust constraints on planetary interior composition and mineralogy beyond those obtainable from mass and radius measurements alone. This framework establishes a physically motivated foundation for linking rocky exoplanet interiors to atmospheric characterization in the JWST era.
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BibTeX
@article{krishna2026stellar,
title = {{Stellar Abundances as Probes of Rocky Exoplanet Interiors: The Mantle Composition and Mineralogy of GJ 486b}},
author = {Harshit Krishna and Asmit Gupta and Sneha Bhowmik and Chandan K. Sahu and Sudipta Mridha and Liton Majumdar},
journal = {The Astrophysical Journal},
year = {2026},
month = oct,
doi = {10.3847/1538-4357/ae9ba8},
url = {https://iopscience.iop.org/article/10.3847/1538-4357/ae9ba8},
note = {CC BY 4.0},
}
RIS
TY - JOUR
TI - Stellar Abundances as Probes of Rocky Exoplanet Interiors: The Mantle Composition and Mineralogy of GJ 486b
AU - Harshit Krishna
AU - Asmit Gupta
AU - Sneha Bhowmik
AU - Chandan K. Sahu
AU - Sudipta Mridha
AU - Liton Majumdar
PY - 2026
DA - 2026/10/01
JO - The Astrophysical Journal
DO - 10.3847/1538-4357/ae9ba8
UR - https://iopscience.iop.org/article/10.3847/1538-4357/ae9ba8
AB - Over the past three decades, hundreds of rocky exoplanets have been discovered. Some of these show atmospheric signatures indicative of diverse chemical compositions. Interpreting these atmospheres requires a physically grounded understanding of planetary interiors, as interior composition and mineralogy govern the formation and evolution of secondary atmospheres. Rocky terrestrial exoplanets are expected to inherit the refractory composition of their host stars, providing a direct pathway to constrain their bulk composition and mineralogy. However, a large fraction of these planets orbit M-type stars, whose compositions remain poorly constrained because of limited and uncertain stellar abundance measurements. Here, we present a physically consistent framework that connects stellar abundances to the interior structure and mineralogy of rocky exoplanets by combining stellar abundance inference, devolatilization modeling to estimate bulk and mantle elemental abundances, interior structure calculations to derive pressure–temperature ( P – T ) profiles, and thermodynamic equilibrium modeling of mantle mineralogy. We first benchmark the framework against Earth and then apply it to the super-Earth GJ 486b using chemically consistent abundances derived from ensembles of similar M-dwarf hosts. We find that GJ 486b likely hosts an iron-rich and silica-poor mantle relative to Earth while preserving the major mantle phase transitions. Sensitivity analyses show that the overall mineralogical structure is robust to variations in bulk composition and P – T profiles, with temperature primarily modulating phase proportions near key transitions. Our results demonstrate that stellar chemical abundances, when combined with physically motivated devolatilization models, provide robust constraints on planetary interior composition and mineralogy beyond those obtainable from mass and radius measurements alone. This framework establishes a physically motivated foundation for linking rocky exoplanet interiors to atmospheric characterization in the JWST era.
SN - 0004-637X
SN - 1538-4357
ER -