Issue |
A&A
Volume 698, May 2025
|
|
---|---|---|
Article Number | L1 | |
Number of page(s) | 8 | |
Section | Letters to the Editor | |
DOI | https://doi.org/10.1051/0004-6361/202554506 | |
Published online | 23 May 2025 |
Letter to the Editor
Unraveling the origin of giant exoplanets
Observational implications of convective mixing
Department of Astrophysics, University of Zurich, Winterthurerstrasse 190, CH-8057 Zurich, Switzerland
⋆ Corresponding author: henrik.knierim@uzh.ch
Received:
12
March
2025
Accepted:
16
April
2025
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 MJ, 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.
Key words: convection / planets and satellites: atmospheres / planets and satellites: composition / planets and satellites: gaseous planets / planets and satellites: interiors / planets and satellites: physical evolution
© The Authors 2025
Open Access article, published by EDP Sciences, under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
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