✎ recherche:projets:wavesmagnetizedstars[CBP]

✎ recherche:projets:wavesmagnetizedstars

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  * [[recherche:projets|Projets soutenus]]

====== Waves in the radiative zones of rotating magnetized stars ======

{{:recherche:wavesstars.png?nolink&250 |}} Service AstroPhysique (Sap), IRFU, CEA Saclay : A.Valade, V.Prat, S.Mathis, K.Augustson\\
Centre Blaise Pascal : Emmanuel Quémener

To have a full understanding of the dynamics of stellar and planetary systems, 
we cannot consider them as only interacting rotating solid bodies. Indeed, a 
more nuanced approach includes the interactions through processes such as 
internal energy dissipation due to tidal coupling between the star and its 
planets, and even between the planets themselves. 

The studies of these internal waves have now reached a level of
accuracy that leads us to consider low amplitude but complex magnetic
fields. We thus aim to develop an asymptotic short-wavelength theory
for waves in radiative zones of rotating stars with a general magnetic
field topology.  Such a theory permits the characterization of fossil
magnetic fields inside of the star, whereas they are normally
observable only at the star's surface.

A dispersion relationship has already been derived for a uniformly rotating 
polytropic star with a low Alfvén speed. Two families of waves are evident 
in the analysis: gravito-inertial waves perturbed by a magnetic field and 
Alfvén waves perturbed by gravity and rotation. We now aim to explore the 
parameter space for such waves in this model with a Hamiltonian ray-tracing 
method. This numerical approach consists of following the paths of rays in
the interior of a star, and then analyzing their characteristics through various 
representations: as plots of their spatial trajectories, phase-space diagrams 
(more widely known as Poincaré sections), and describing zones where the 
waves are able to propagate. Most of these analyses require the computation 
of a large number of rays, leading us to use parallel computing methods on 
supercomputers.

====== Contribution du CBP ======

Le Centre Blaise Pascal met à disposition son plateau technique multi-shaders pour :
  * offrir un large panel de GPU ou GPGPU pour établir une comparaison pertinente
  * permettre la caractérisation de différents GPU pour une application donnée
  * évaluer l'intégration de traitements automatisés sur le plateau technique multi-noeuds