Séminaire IPAG

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Understanding the magneto-rotational evolution of stars

jeudi 21 octobre 2021 - 11h00

Antoine Strugarek - CEA
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The magnetic field of our Sun is generated through an internal dynamo process leading to a cyclic variability of about 11 years. This cyclic field shapes the environment of our star and determines the connectivity in the heliosphere from the photosphere to the Earth orbit and beyond. The Sun has probably not always possessed such a cyclic field, nor should it keep it as it ages. Indeed, stars like the Sun spin down as they age, which greatly influences the dynamo processes they are able to sustain. I will present ongoing efforts to model stellar dynamos in an evolutionary context. Based on numerical studies, we have recently proposed a unified view of the types of cycles solar-like stars are able to sustain. These results are confirmed using both simplified, mean field approach as well as 3D turbulent numerical simulations using various approximations. They show a tight link between the large-scale rotation profile within solar-like star, and the type of cyclical dynamos they are able to sustain. In this context I will detail the expected energy budget of such stars, and its implication for stellar dynamos. I will finally end with recent efforts where we start coupling dynamo action acting over decadal timescales with the response of the environment of the star, its dynamical corona. 

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Hôtes : Benoît Cerutti

Salle Manuel Forestini, 414 rue de la piscine, 38400 Saint Martin d'Hères