Constraining the origin of giant exoplanets via elemental abundance measurements

Abstract

The origin of close-in giant planets is a key open question in planet formation theory. The two leading models are (i) formation at the outer disk followed by migration and (ii) in situ formation. In this work we determine the atmospheric composition of warm Jupiters for both formation scenarios. We perform N-body simulations of planetesimal accretion interior and exterior to the water ice-line for various planetary formation locations, planetary masses, and planetesimal sizes to estimate the accreted heavy-element mass and final planetary composition. We find that the two models differ significantly: migrating giant planets have 2-14 times higher metallicities than planets that form in situ. The ratio between refractories and volatiles is found to be above one for migrating planets but below 0.4 for planets that form in situ. We also identify very different trends between heavy-element enrichment and planetary mass for these two formation mechanisms. While the metallicity of migrating planets is found to increase with decreasing planetary mass, it is about constant for in situ formation. Our study highlights the importance of measuring the atmospheric composition of warm Jupiters and its connection to their formation and evolutionary paths.

published in A&A, 5 pages, including 4 figures, plus 2 pages appendix; v2 follows the A&A language guidelines

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• Searching for Giant Exoplanets around M-dwarf Stars (GEMS) I: Survey Motivation
• Enriching inner discs and giant planets with heavy elements
• Composition of giant planets: the roles of pebbles and planetesimals
• A new dynamical modeling of the WASP-47 system with CHEOPS observations
• Convective Mixing in Gas Giant Planets with Primordial Composition Gradients
• Unraveling the origin of giant exoplanets: Observational implications of convective mixing
• Evidence of Titanate Clouds in the Day-side Atmosphere of the Ultra-Hot Jupiter WASP-121b
• Investigating the eccentricity distribution of transiting, long-period giant planets
• Icy Volatile Enhancements in Evolving Protoplanetary Disks