Unraveling the origin of giant exoplanets: Observational implications of convective mixing

Fuente: arXiv
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Main Authors: Knierim, Henrik, Helled, Ravit
Format: Preprint
Published: 2025
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author Knierim, Henrik
Helled, Ravit
author_facet Knierim, Henrik
Helled, Ravit
contents The connection between the atmospheric composition of giant planets and their origin remains elusive. In this study, we explore how convective mixing can link the primordial planetary state to its atmospheric composition. We simulate the long-term evolution of gas giants with masses between 0.3 and 3 Jupiter masses, considering various composition profiles and primordial entropies (assuming no entropy-mass dependence). Our results show that when convective mixing is considered, the atmospheric metallicity increases with time and that this time evolution encodes information about the primordial planetary structure. Additionally, the degree of compositional mixing affects the planetary radius, altering its evolution in a measurable way. By applying mock observations, we demonstrate that combining radius and atmospheric composition can help to constrain the planetary formation history. Young systems emerge as prime targets for such characterization, with lower-mass gas giants (approaching Saturn's mass) being particularly susceptible to mixing-induced changes. Our findings highlight convective mixing as a key mechanism for probing the primordial state of giant planets, offering new constraints on formation models and demonstrating that the conditions inside giant planets shortly after their formation are not necessarily erased over billions of years and can leave a lasting imprint on their evolution.
format Preprint
id arxiv_https___arxiv_org_abs_2504_12118
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Unraveling the origin of giant exoplanets: Observational implications of convective mixing
Knierim, Henrik
Helled, Ravit
Earth and Planetary Astrophysics
The connection between the atmospheric composition of giant planets and their origin remains elusive. In this study, we explore how convective mixing can link the primordial planetary state to its atmospheric composition. We simulate the long-term evolution of gas giants with masses between 0.3 and 3 Jupiter masses, considering various composition profiles and primordial entropies (assuming no entropy-mass dependence). Our results show that when convective mixing is considered, the atmospheric metallicity increases with time and that this time evolution encodes information about the primordial planetary structure. Additionally, the degree of compositional mixing affects the planetary radius, altering its evolution in a measurable way. By applying mock observations, we demonstrate that combining radius and atmospheric composition can help to constrain the planetary formation history. Young systems emerge as prime targets for such characterization, with lower-mass gas giants (approaching Saturn's mass) being particularly susceptible to mixing-induced changes. Our findings highlight convective mixing as a key mechanism for probing the primordial state of giant planets, offering new constraints on formation models and demonstrating that the conditions inside giant planets shortly after their formation are not necessarily erased over billions of years and can leave a lasting imprint on their evolution.
title Unraveling the origin of giant exoplanets: Observational implications of convective mixing
topic Earth and Planetary Astrophysics
url https://arxiv.org/abs/2504.12118