Séminaire ISTerre

Exoplanetary magnetic fields as a tool for future interior characterization

mardi 30 juin 2020 - 10h00
Irène Bonati - Earth and Life Science Institute, Tokyo
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Most planets located within our solar system display evidence of past and/or current magnetic activity. Magnetic fields of rocky bodies are thought to be driven by thermo-chemical convection taking place in an electrically conducting fluid in their deep interior (the liquid core for Earth), and are thus evidence of strong internal dynamics. Furthermore, magnetism is thought to play a crucial role for the development and the long-term stability of habitable surface conditions, as it shields the upper atmosphere from mass loss induced by stellar winds and extreme space weather events.

The discovery of a large number of rocky exoplanets motivates the search and the study of magnetic fields beyond the solar system. While current observations are limited to providing the planetary radius and minimum mass, the future exploration of exoplanetary atmospheres will open up new avenues for the inversion of interior properties starting from atmospheric parameters. Such a goal requires knowledge of the cores and magnetic fields of exoplanets, as well as their influence on atmospheric evolution.

In the current study we investigate the evolution of the cores of planets having different mass and iron content. Starting out from the internal temperature profile after the complete solidification of a global magma ocean, we determine the size and structure of the core, and model its subsequent thermal and magnetic evolution. We compute the thermal and compositional buoyancy fluxes, as well as the generated magnetic field strength and lifetime. We also vary the content of light alloys and determine their effect on the evolution of an inner core and the lifetime of the field. While the planetary mass does not seem to be a determining factor, we find that iron-rich planets having a high mantle iron number and high light element concentration start out and end up with inner cores that are substantially larger than iron-poor bodies, sometimes reaching up the radius of the outer core and shutting down magnetic activity. We therefore find that there is a “sweet spot” for longer-lasting magnetic fields. Field strengths can reach up to several times the one of Earth, even though such a signal might still be too weak to be detected by current instrumentation.

Equipe organisatrice : Géodynamo

Séminaire uniquement en visio

Informations de visio :

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“Minimalist seismology”: studying earthquakes with sparse instrumentation

jeudi 17 septembre 2026 - 11h00

Mathieu Causse - ISTerre

Equipe organisatrice : Organisation labo

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Stable‑to‑dynamic expansion of fault slipping area through fluid injection observed in laboratory experiments using a sub‑meter scale specimen

vendredi 18 septembre 2026 - 14h00

Takatoshi Ito  - Université de Tohoku, Japan

Equipe organisatrice : Mécanique des failles

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Tectonics, Mantle Dynamics and Coupled Lithosphere-Mantle-Core Evolution of Earth and Other Rocky Worlds

jeudi 24 septembre 2026 - 11h00

Paul Tackley - ETH Zurich

Equipe organisatrice : Grands Séminaires ISTerre

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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Apport des expériences analogiques pour la modélisation et le suivi en temps réel de la propagation du magma en profondeur : Exemple du Rift Est Africain

jeudi 1er octobre 2026 - 11h00

Virginie Pinel - ISTerre

Equipe organisatrice : Organisation labo

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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A t-on encore besoin de plaques pour expliquer la tectonique de la vallée du Rhône et des Alpes Occidentales ?

vendredi 2 octobre 2026 - 11h00

philippe VERNANT - Geosciences Montpellier

Equipe organisatrice : Tectonique active et sismicité

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 2 octobre 2026 - 14h00

Hugo Boulze - 

Equipe organisatrice : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 9 octobre 2026 - 11h00

Eric Beaucé - ISTerre

Equipe organisatrice : Cycle sismique et déformations transitoires

Salle Dolomieu, Maison des Géosciences, 38400 Saint Martin d'Hères

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TBA

vendredi 20 novembre 2026 - 11h00

Farzaneh Mohammadi - ENS Paris

Equipe organisatrice : Cycle sismique et déformations transitoires

Amphithéâtre Killian, Maison des Géosciences, 38400 Saint Martin d'Hères

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