Whereas the birth of stars can be quiet, their demise may be cataclysmic, leaving remnants with extraordinary properties: pulsars, black holes, micro-quasars… Dapnia is interested in all stages of their life cycle, including our own Sun.
maj : 07-02-2005 (550)
Compact objects (black holes, neutron stars and white dwarfs) play a major role in modern astrophysics. They are associated with the most exotic environments and violent phenomena of the Universe. Surrounded by extremely powerful gravitational and magnetic fields, they appear as luminous X-ray or gamma-ray sources, thus allowing scientists to explore certain physical processes under conditions that cannot be obtained in laboratories. Astrophysicists involved in the study of compact objects focus on a number of key ... Lire la suite »
Studying galactic cosmic rays was one of the original choice topics in CEA’s Service d’Astrophysique (SAp). Far from being resolved, the origin of cosmic rays raises topical questions about the energy source capable of sustaining this population, about the acceleration mechanism at work, about the maximum energy and spectral form given to particles by this mechanism and finally about the required number of different accelerator types. Is it possible to reproduce the observations using a single type of ... Lire la suite »
Most of the known matter in the Universe is in the form of plasma. Astrophysical phenomena affect the properties of plasma in conditions that, because of their extremes of density, temperature or speed, are unknown on Earth. The study some of these properties, detected in the Sun by seismology, uses the modelling of dynamic phenomena and 3D simulation. The GOLF space instrument is playing an important part in this, through the discovery of a signature for gravity modes, low-frequency waves produced by upthrust, for ... Lire la suite »