Detailed chemical compositions of planet-hosting stars: II. Exploration of the interiors of terrestrial-type exoplanets

Abstract

A major goal in the discovery and characterisation of exoplanets is to identify terrestrial-type worlds that are similar to (or otherwise distinct from) our Earth. Recent results have highlighted the importance of applying devolatilisation -- i.e. depletion of volatiles -- to the chemical composition of planet-hosting stars to constrain bulk composition and interiors of terrestrial-type exoplanets. In this work, we apply such an approach to a selected sample of 13 planet-hosting Sun-like stars, for which high-precision photospheric abundances have been determined in the first paper of the series. With the resultant devolatilised stellar composition (i.e. the model planetary bulk composition) as well as other constraints including mass and radius, we model the detailed mineralogy and interior structure of hypothetical, habitable-zone terrestrial planets ("exo-Earths") around these stars. Model output shows that most of these exo-Earths are expected to have broadly Earth-like composition and interior structure, consistent with conclusions derived independently from analysis of polluted white dwarfs. The exceptions are the Kepler-10 and Kepler-37 exo-Earths, which we predict are strongly oxidised and thus would develop metallic cores much smaller than Earth. Investigating our devolatilisation model at its extremes as well as varying planetary mass and radius (within the terrestrial regime) reveals potential diversities in the interiors of terrestrial planets. By considering (i) high-precision stellar abundances, (ii) devolatilisation, and (iii) planetary mass and radius holistically, this work represents essential steps to explore the detailed mineralogy and interior structure of terrestrial-type exoplanets, which in turn are fundamental for our understanding of planetary dynamics and long-term evolution.

Accepted for publication in MNRAS; 19 pages, 14 figures, 2 tables; a related talk is available at https://www.youtube.com/watch?v=n0TPQ2IrAyA

References in corpus (25)

• Seven temperate terrestrial planets around the nearby ultracool dwarf star TRAPPIST-1
• A terrestrial planet candidate in a temperate orbit around Proxima Centauri
• Can we constrain interior structure of rocky exoplanets from mass and radius measurements?
• High-precision abundances of elements in solar twin stars: Trends with stellar age and elemental condensation temperature
• The composition of Mars
• A generalized bayesian inference method for constraining the interiors of super Earths and sub-Neptunes
• The New Generation Planetary Population Synthesis (NGPPS). I. Bern global model of planet formation and evolution, model tests, and emerging planetary systems
• Oxygen fugacities of extrasolar rocks: Evidence for an Earth-like geochemistry of exoplanets
• The Elemental Abundances (with Uncertainties) of the Most Earth-like Planet
• C/O Ratios of Stars with Transiting Hot Jupiter Exoplanets
• A new class of Super-Earths formed from high-temperature condensates: HD219134 b, 55 Cnc e, WASP-47 e
• Chemical Fingerprints of Formation in Rocky Super-Earths' Data
• A new perspective on interiors of ice-rich planets: Ice-rock mixture instead of ice on top of rock
• The PLATO field selection process I. Identification and content of the long-pointing fields
• Atmospheric characterization of terrestrial exoplanets in the mid-infrared: biosignatures, habitability & diversity
• Chemical evidence for planetary ingestion in a quarter of Sun-like stars
• Detailed chemical compositions of planet hosting stars: I. Exploration of possible planet signatures
• Characterizing Atmospheres of Transiting Earth-like Exoplanets Orbiting M Dwarfs with James Webb Space Telescope
• Host-star and exoplanet compositions: a pilot study usinga wide binary with a polluted white dwarf
• Exoplanets with ELT-METIS I: Estimating the direct imaging exoplanet yield around stars within 6.5 parsecs
• Detailed elemental abundances of binary stars: Searching for signatures of planet formation and atomic diffusion
• Lithologic Controls on Silicate Weathering Regimes of Temperate Planets
• Evidence for post-nebula volatilisation in an exo-planetary body
• The GALAH Survey: Using Galactic Archaeology to Refine our Knowledge of TESS Target Stars
• Europium as a lodestar: diagnosis of radiogenic heat production in terrestrial exoplanets

Cited by in corpus (10)

• Setting the stage for the search for life with the Habitable Worlds Observatory: Properties of 164 promising planet survey targets
• Plausible constraints on the range of bulk terrestrial exoplanet compositions in the Solar neighbourhood
• A mineralogical reason why all exoplanets cannot be equally oxidising
• Mantle mineralogy limits to rocky planet water inventories
• Observation uncertainty effects on the precision of interior planetary parameters
• Eta-Earth Revisited II: Deriving a Maximum Number of Earth-like Habitats in the Galactic Disk
• The chemical evolution of the solar neighbourhood for planet-hosting stars
• Diversity of Exoplanets
• The impact of incorrect dissociation energies on inferred photospheric abundances
• Chemical Abundances Shape History (CASH). I. A Link between Giant Planets Orbital Periods and Host Stellar C/O Ratios