The origin of the high heavy-element content of warm Jupiters
Year: 2026
Type: article
Abstract: Interior models of planets have revealed that warm Jupiters should harbour high heavy-element masses, with Jupiter mass planets potentially consisting of up to 30-40% of heavy elements (heavier than hydrogen and helium). However, it is unclear whether the heavy-element mass of giant planets decreases with decreasing stellar mass. Within the pebble drift and evaporation scenario, inward-drifting pebbles can evaporate, enriching the inner disc with vapour to super-stellar values, which can then be accreted by growing giant planets. Due to a sequential evaporation sequence -- where H_2O evaporates in the inner disc, while CO_2, CH_4, and CO evaporate in the outer disc -- the vapour enrichment of the disc decreases with increasing orbital distance. We employed the code to model the migration and growth of planets via pebble and gas accretion in discs around stars of different masses and discs of different sizes. Our simulations show that: (i) pebble drift and evaporation can explain the wide range of derived heavy-element content in giant planets; (ii) giant planets forming around stars with larger disc sizes can accrete larger quantities of heavy elements, because these discs can maintain a high pebble flux for a longer time, allowing the inner discs to be enriched for longer and resulting in planets with higher heavy-element content; (iii) planets forming or migrating interior to the water ice line can accrete larger amounts of heavy elements via the accretion of vapour-enriched gas compared to those forming in the outer disc regions; (iv) metal-rich stars can enable the formation of planets more enriched in heavy elements if they form in the inner disc regions, whereas planets forming in the outer disc regions -- regardless of disc metallicity -- are much less enriched than their inner-disc counterparts that accrete vapour-enriched gas; and (v) planets forming in discs with the same size and total mass but around higher-mass stars are only marginally more enriched than those forming around lower-mass stars. Together, our study suggests that the trend of increasing total heavy-element mass with increasing planetary mass arises from the accretion of vapour-enriched gas in discs of different sizes, combined with the different origins of warm giant planets from the inner and outer disc. chemcomp
Source: Astronomy and Astrophysics
Author: Bertram Bitsch
Language: English
Topic: Astro and Planetary Science
Subfield: Space and Planetary Science
Field: Earth and Planetary Sciences
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W7223108632