Magique 3D and the modelling of the Sun
How is the Sun constituted? It is difficult to say with any certainty. Although it has been possible to carry out probes and measurements on certain stars (such as the planet Mars), the same cannot be applied to the Sun - the central star of the solar system – due to the fact that it is too hot and too far away.
Helioseismologists from the Max Planck Institute in Göttingen (the equivalent of the CNRS in France) are working on solving this mystery and, to do this, they are studying the propagation of acoustic waves that inform them about the nature of this environment. "These waves spread within the Sun thanks to the presence of particles, Juliette Chabassier of Magique 3D points out. Once they reach the Sun's surface, they induce electromagnetic rays that are captured and reproduced as measurements by a space station (Soho), positioned between the Earth and the Sun in 1995, and then the SDO (Solar Dynamics Observatory), which has been in geostationary orbit since 2010. These measurements allow us to find out the velocity of the points located on the Sun's surface that we can see. They then enable us to carry out seismology research".
The measurements don't exactly “fall from the sky”. In order to exploit them, Magique 3D has provided its German partners with a software solution to solve wave propagation equations in the Sun, and a second software solution for inverse problems such as "given the observations made about the Sun, how is the medium constituted?". Armed with great expertise with regard to the modelling of wave phenomena, the Pau-based project team has adapted certain tools already at its disposal. It also seeks to develop new and very innovative functionalities, relating to the specific case of the Sun, "an environment that is constantly evolving, characterised by convection and turbulence, and where nuclear reactions take place". On the German side, this long-term project has been awarded a European Research Council grant; support that is synonymous with a mark of confidence from Europe.