Next-Generation of Interior models of (Exo)planets:Studying the interior structure of giant planets and its effect on their evolution, atmospheres and observations

Informations projet

N-GINE

N° de convention de subvention: 101088557

DOI

10.3030/101088557

Date de signature de la CE 3 Mars 2023

Date de début 1 Septembre 2023

Date de fin 31 Août 2028

Financé au titre de

• European Research Council (ERC)

Coût total

€ 1 998 802,00

Contribution de l’UE

€ 1 998 802,00

Coordonné par

STICHTING NEDERLANDSE WETENSCHAPPELIJK ONDERZOEK INSTITUTEN
Netherlands

Periodic Reporting for period 1 - N-GINE (Next-Generation of Interior models of (Exo)planets:Studying the interior structure of giant planets and its effect on their evolution, atmospheres and observations)

Période du rapport: 2023-09-01 au 2026-02-28

Résumé du contexte et des objectifs généraux du projet

Planets are among the most fascinating objects in the Universe, yet our understanding of how they form and evolve remains incomplete. For a long time, scientists believed that the four giant planets in our Solar System, Jupiter, Saturn, Uranus and Neptune, offered a universal template for planetary formation. However, the discovery of thousands of planets around other stars has completely changed this view. The diversity of these “exoplanets” is astonishing: some are larger than Jupiter but orbit very close to their stars, while others are smaller and much colder. This variety has revealed the limitations of our current models and raised new questions about how planets are built, what they are made of, and how they change over time.

The N-GINE project (New-Generation Interior and Evolution models for planets) was designed to address these fundamental questions. It bridges Solar System and exoplanet science by developing a new generation of models that link a planet’s interior structure with its atmosphere and long-term evolution. The goal is to build a unified physical framework that can explain both the planets we know best (those in our own Solar System) and the thousands of new worlds now being discovered.

The project’s main objectives are to (1) develop advanced models that describe the interior structure of our solar system giant planets and exoplanets, (2) understand the physical and chemical interactions between a planet’s interior and atmosphere, and (3) connect these internal processes to the signals observed by telescopes such as JWST, HST, Cheops and TESS. By doing so, N-GINE provides the scientific tools needed to interpret current and future planetary observations and to guide upcoming missions led by the European Space Agency and NASA.

Beyond its scientific goals, the project contributes to Europe’s leadership in exoplanet research and supports the training of the next generation of planetary scientists. By combining theory, modelling and observation, N-GINE strengthens the link between fundamental science and the rapidly expanding field of space exploration.

Travail effectué depuis le début du projet jusqu’à la fin de la période considérée dans le rapport et principaux résultats atteints jusqu’à présent

During its implementation, N-GINE has achieved several key scientific milestones. One of the project’s main achievements is the development of the first retrieval framework capable of deducing an exoplanet’s internal composition directly from observable quantities such as its mass, radius and atmospheric properties. This model introduces an innovative parameter known as the Love number, which describes how a planet deforms under the gravitational pull of its star. The new framework represents a world-first and establishes a new methodology for understanding the deep interiors of planets far beyond our Solar System.

Another major success concerns the composition of Neptune, one of the least understood planets in our Solar System. By adapting models originally developed for Jupiter and Saturn, the N-GINE team discovered that Neptune’s envelope is likely dominated by rocky material rather than ices, as was long believed. This unexpected result, marks a paradigm shift in planetary science and challenges decades of assumptions about the “ice giants.”

The project has also solved a long-standing mystery about why Jupiter and Saturn rotate in one direction while Uranus and Neptune rotate in the opposite. Through advanced simulations and theoretical modelling, N-GINE developed the first unified theory of atmospheric circulation capable of explaining this behaviour. The results, published in Science Advances, resolve a question that had remained unanswered for decades and offer new insights applicable to exoplanet atmospheres as well.

In addition, the team demonstrated how atmospheric escape (the loss of light gases such as hydrogen and helium) can enrich planets in heavy elements over time, shaping their observed properties. This research, associated with a highly competitive joint JWST–HST observing program, will lead to the first young exoplanet ever observed by all major space telescopes currently in operation.

Beyond its scientific breakthroughs, N-GINE has produced valuable community resources, including open-access opacity tables for Jupiter and Saturn and publicly available codes hosted on GitHub. The project’s results have been presented at major international conferences such as Exoplanets V, Exoclimes, EGU, EPSC–DPS and COSPAR, ensuring global visibility and impact.

The ERC funding has also enabled the creation of a strong, international, interdisciplinary research group. The team now includes postdoctoral researchers and students working on both Solar System and exoplanet science, generating a collaborative environment that fosters innovation and discovery.

Progrès au-delà de l’état des connaissances et impact potentiel prévu (y compris l’impact socio-économique et les conséquences sociétales plus larges du projet jusqu’à présent)

The N-GINE project has delivered discoveries that go well beyond the current state of knowledge and that will shape the future of planetary science.

The retrieval framework developed by the team represents the first tool capable of combining planetary structure and tidal deformation to infer interior properties from observational data. While interior modelling was part of the project’s original plan, the integration of Love numbers emerged unexpectedly and opened entirely new research directions. This innovation has already inspired new telescope proposals and secured dedicated JWST observing time, positioning Europe at the forefront of exoplanet characterization.

The unified theory of planetary circulation developed by N-GINE provides, for the first time, a coherent physical explanation for the atmospheric motions of all four giant planets. It connects interior dynamics with atmospheric flows and provides predictive power for exoplanets yet to be observed by ESA’s PLATO mission.

The finding that Neptune’s envelope is likely rock-dominated redefines our understanding of the Solar System. This discovery forces a re-evaluation of how planets form and what materials dominate their interiors. It challenges the traditional classification of Uranus and Neptune as “ice giants” and suggests new pathways for the evolution of planets across the galaxy.

Together, these advances mark a significant leap forward in planetary science. They provide a new generation of models and open-access resources that will remain valuable to the scientific community well beyond the lifetime of the project. Looking ahead, future research will focus on expanding these models to cover a wider diversity of planets and integrating them with upcoming space missions.

The N-GINE project exemplifies how curiosity-driven research, supported by the European Research Council, can deliver discoveries that fundamentally change our understanding of the Universe—linking the study of our Solar System to the thousands of worlds orbiting other stars.