The WholeSun Program

Understanding the physical mechanisms behind the eruptive activity of the Sun and its stellar twins

Program duration: From 02/03/2020 to 27/03/2020

Organised by Dr. (HDR) Allan Sacha Brun, Director of Research CEA. Head of the Laboratory Dynamics of Stars, (Exo)-planets and their Environment (LDE3), Coordinating PI de l'ERC Synergy Whole Sun (


About the WholeSun project

This project unites European experts concerned with the Sun and stars, from the Astrophysics Department of CEA-Irfu / UMR AIM in France, the Max Planck Institute for Solar System Research (MPS) in Germany, the University of St Andrews in the United Kingdom and the University of Oslo in Norway. Together they pool their know-how and knowledge of the dynamics of our star and its twin stars. The objective is to determine over the next six years how the magnetic field is generated inside the Sun and how it creates solar spots on its surface and eruptions in its highly stratified atmosphere. To this end, the team will develop the most advanced complete Sun model using the most powerful supercomputers, known as Exa-scale, and will constrain it with observations from space missions, such as the European Space Agency's (ESA) Solar Orbiter, to be launched in 2020.


Aims of  the WholeSun project

Mission: Despite decades of intense research, most fundamental questions remain unanswered, such as "How does the Sun work?", "Why does it have a magnetic cycle, blackheads and a dynamic hot atmosphere?". Through the Whole Sun project, we wish to address these key questions for the first time as a coherent whole. 


Vision: Solar activity, with its many manifestations and eruptions of magnetized clouds and particles, has a direct impact on our technological society. Understanding it is therefore a major societal challenge. "The WholeSun project is an innovative multidisciplinary approach in solar physics that will lead to successful collaborations in Europe," predicts Professor Eric Priest of the University of St Andrews. Indeed, in recent decades, research in solar physics has focused on studying the structure and dynamics of the interior of the Sun or the solar surface/atmosphere. The objective is to consolidate the studies of these two major solar regions, through strong synergies between the team members, in order to acquire an advanced understanding of their coupling and the Sun. "The detailed study of the (thermo)dynamic and magnetic coupling between the core of the Sun, the solar surface and the highly stratified atmosphere is absolutely essential if we want to address the key and open problems of solar physics" argues Dr. Antoine Strugarek (DAp-AIM) involved in the project.

The WholeSun project is made possible by advancements in supercomputing. “The project will develop numerical models of the whole Sun that will run on exascale supercomputers that perform a billion billion arithmetic operations per second”, explains Principal Investigator Allan Sacha Brun from CEA Saclay France. The numerical models will be used in combination with observations to tackle many unsolved mysteries in solar physics. For example, it is not known how sunspots are formed, nor what triggers the most energetic solar flares.

Violent solar eruptions throw charged particles and radiation into space. "The origin of all the eruptive phenomena that we observe in the Sun’s atmosphere, however, lies much deeper within our star," explains Professor Laurent Gizon, one of the Principal Investigators of WholeSun.


Program content:

  • WP1 & WP5: 02/03/2020 to 20/03/2020 (solar convection and dynamo, helioseismology and stellar physics and asteroseismology)
  • WP2, WP3 & WP4: 09/03/2020 to 27/03/2020 (flux emergence, low corona dynamics, jets and eruptive events)
  • WPX: 02/03/2020 to 27/03/2020 (new global solar code development)

For further information about the WholeSun Project, please click here