Beyond the convection dynamo paradigm
David Cébron
(ISTerre, Grenoble)
| Quand ? |
Le 19/03/2019, de 10:45 à 11:45 |
|---|---|
| Où ? | room 115 |
| Participants |
David Cébron |
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The Earth's global magnetic field comes from motions in its metallic liquid core (via a dynamo effect). These flows are commonly attributed to thermo-solutal convection, and the corresponding simulations are in broad agreement with observations. However, this model is challenged by the possible presence of a stratified layer in the core, by the thermally stratified core of the Early Earth, and by the Moon paleofield strength (too large for the convection model). In this seminar, I will rapidly present different studies led at ISTerre on these questions. In particular, I will focus on stratified planetary cores, studying the double-diffusive convection proposed for the Early Earth core, and the precession driven dynamo proposed for the Early Moon. Tidally driven dynamos in stratified fluids, such as radiative stars, will finally be tackled.