Description du projet
Découvrir le mécanisme des champs magnétiques ordonnés dans l’Univers
Les champs magnétiques imprègnent une grande partie du cosmos. Fait remarquable, presque tous les corps célestes dotés de champs magnétiques ne présentent pas une toile enchevêtrée, mais plutôt une structure magnétique ordonnée. Les champs magnétiques ordonnés sont si répandus dans notre univers chaotique que les astronomes, qui veulent découvrir leur provenance et comprendre comment ils persistent dans ce chaos, sont déconcertés. Les théories les plus avancées ne peuvent pas expliquer de manière satisfaisante comment survient cet ordre, en particulier dans les étoiles de type solaire comme notre Soleil. Le projet UniSDyn, financé par l’UE, prévoit de développer de nouvelles simulations et de nouveaux outils d’analyse des données afin de décrire plus précisément les processus de dynamo dans les objets célestes, à savoir les mécanismes qui leur permettent de générer des champs magnétiques.
Objectif
Magnetic fields are ubiquitous in the universe. The special property of cosmic magnetism is that, in the majority of objects hosting magnetic fields, those fields are organized, such that some meaningful averaging can reveal global structure and systematic behavior. In the Sun, averaging over longitude reveals the equatorward migration of the emergence region of the sunspots, forming the famous butterfly diagram. Further, vigorous turbulence is present in a wide variety of astrophysical systems, and yet they still exhibit organized magnetic fields. These observations prompt the search for a theory to explain how order can arise and sustain itself in such chaos. We claim that the available theories are incomplete, especially in the case of solar-like stars which becomes apparent if we view the Sun as one star among many. We propose a coherent plan of advancement in which each theory shall be tested by requiring it also to explain the cyclic dynamo action seen in more active rapid rotators.
UNISDYN project attacks these very problems with novel simulations and data analysis tools. Our path to resolve them is to enhance the state-of-the-art stellar dynamo models with the relevant descriptions of the turbulent processes. This goal is reached in three steps. (i) We will produce improved convection dynamo simulations to serve as laboratories from which (ii) the turbulent transport coefficients are directly measured with a novel test methods suite. (iii) Finally, global dynamo models incorporating the turbulent effects in full are constructed based on (i) and (ii) results. These results will allow us to unify stellar dynamo theory for solar-like inactive and rapidly rotating active stars. The developed toolbox has direct applications in other fields of astrophysics, such as accretion and galactic disk dynamos, and industry, such as combustion engines and fusion reactors.
Champ scientifique
Programme(s)
Régime de financement
ERC-COG - Consolidator GrantInstitution d’accueil
02150 Espoo
Finlande