1,2,3,7Harshit Krishna, 1,2,4,7Asmit Gupta, 1,2,5Sneha Bhowmick, 1,2,6Chandan K. Sahu, 1,2Sudipta Midha, 1,2Liton Majumdar
The Astrophysical Journal, 1010, 23
Open Access Link to Article [DOI: 10.3847/1538-4357/ae9ba8]
1Exoplanets and Planetary Formation Group, School of Earth and Planetary Sciences, National Institute of Science Education and Research, Jatni 752050, Odisha, India
2Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, India
3Department of Physical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Knowledge City, Sector 81, Sahibzada Ajit Singh Nagar, Punjab 140306, India
4Indian Institute of Science Education and Research, Kolkata, Mohanpur 741246, West Bengal, India
5Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, India
6Department of Geosciences, Pennsylvania State University, University Park, State College, PA 16802, USA
7Harshit Krishna and Asmit Gupta contributed equally to this work.
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.
