Laboratoire Univers et Théories

Astrophysique Multi-Echelle (Equipe AME)

01 Fundamental Physics

The study of astrophysical phenomena rests on fundamental physics. The AME team studies in particular radiation transfer problems, atomic physics, plasma physics (solar, stellar, nebular plasmas), foundations of quantum physics (with a proposal for a space experiment), magnetohydrodynamics and stellar dynamo. Work on the fractal structure of the distribution of galaxies and on the prediction of the value of the cosmological constant is carried on within the framework of the theory of scale relativity.

One of the strengths of this team is to use laboratory experiments to confirm the theory. The SHADE team (for Simulations of High Energy Densities team) uses high-power lasers, whereas other researchers define experiments of fundamental physics.

02 SHADE team

During the last decade, a relevant research for astrophysics developed all over the world, using the high-energy density (HED) facilities as intense lasers and Z-pinches. The research is in progress in many domains, as compressible hydrodynamic mixtures, strong shock phenomena, radiation flux, radiative shocks and jets, complex opacities, equations of state (EOS), formation of dust, or very intense magnetic fields and relativist plasmas. The stake in this research field is the modeling of the behavior of matter in the extreme conditions of density and temperature encountered in astrophysical systems. The study of the matter properties in these extreme conditions of density and temperature is relatively recent because it requires large facilities. On one hand in the field of numerical modeling which requires more and more processors, on the other hand in the experimental domain, extreme states are reached using HED facilities. Where experimental data validate modeling and simulation methods in a certain thermodynamic domain.

03 Exchanges of matter in the Universe

The majority of the chemical elements were produced in the cores of stars or during explosions of supernovae. They then started a long journey during which they enriched in metals the various components of the galaxies: clouds of gas and dust, successive generations of stars, protoplanetary systems. Many characteristics of this odyssey are not well known. The AME team contributes to shed light on some of them, in particular through theoretical and numerical modeling in participation with large collaborations. It studies the transport of the elements manufactured in the cores of stars towards the external layers, the relations between stars and the interstellar medium (winds, photoevaporation), as well as the chemical composition of stars, nebulae and the galaxies which results from these exchange processes.

04 Planetary systems and search for life in the Universe

These last decades planetology experienced a double revolution thanks to the exploration of the solar system by space probes and to the discovery of planets outside the solar system. The AME team participates in the search of exoplanets and life in the Universe by proposing experimental concepts, for example with the CoRoT space mission which discovered at least 12 planets to date. It also carried works on the statistical prediction of the orbital elements of (exo-)planetary systems in scale relativity. The Encyclopaedia of Extrasolar Planets (, currently in eight languages), which is used as a world reference and offers many online services, was created by members of the AME team.

« Siphonner » une étoile : reconstitution par laser

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