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Session SF2A

Dernières nouvelles des exoplanètes
X.Delfosse
(LAOG/Observatoire de Grenoble)



Have we seen the dark matter annihilation in the cosmic electron and positron spectra ?
Julien Lavalle
(Dpt. Theor. Phys. Torino Univ.)
We will review the theoretical interpretations of the recent measurements of the positron fraction by PAMELA, and of the sum of electrons plus positrons by ATIC, Fermi and HESS. We will discuss the relevance of each of them.


Voyage vers l'origine des aurores polaires avec la mission THEMIS/Journey to the origin of the polar aurorae with the THEMIS mission
Le Contel, Olivier
(Laboratoire de Physique des Plasmas, CNRS/Ecole Polytechnique/UPMC/Paris-Sud 11)
The five satellites of the THEMIS mission were launched on February 17, 2007 by NASA. This mission was proposed by the Space Science Laboratory (SSL) of the University of California at Berkeley (UCB), where 3 of the 5 onboard instruments have been built. LPP provided the tri-axis search coil magnetometer, tailored to measure magnetic field fluctuations. CESR/CDPP (Toulouse) is in charge of a data centre that mirrors the UCB data centre. This French participation has benefited from the support of CNES. THEMIS mission aims at determining what triggers geomagnetic substorms leading to intense australis and borealis aurorae. It has been known for quite a long time that aurorae are due to charged energetic particles, electrons and ions, hitting and exciting atmospheric atoms and molecules, in the upper atmosphere of high latitude regions. Charged particles precipitation, in the auroral region, occurs every 3 hours, in average, during explosive phenomena called substorms. During substorms these particles, usually trapped by the Earth's magnetic field, are accelerated from a few eV to a few keV towards the Earth, while the magnetic configuration, at large distances from the Earth, is strongly modified. These energetic particles are coming from a giant reservoir of plasma, called the plasma sheet, and located far away from the Earth, in the night sector, typically at 7-30 Earth radii, and beyond. In this region the terrestrial magnetic field is strongly deformed and forms a magnetic tail. Yet the origin of this acceleration and of breaking of the magnetic confinement, during substorms, is still unclear. Every 4 days, THEMIS's constellation is lined up along the Sun-Earth line and collects coordinated measurements. These in-situ measurements are replaced in a more global context thanks to a network of ground-based all sky cameras and magnetometers, located in Canada and the north of United States. Indeed, the orbits are such that when the THEMIS satellites are nearly aligned their magnetic footprints are above the ground-based network. Thus the network provides a very interesting global mapping of the regions crossed by the satellites. Recent results from the THEMIS mission will be reviewed.


Presentation de la Societe Francaise d'Exobiologie
Francois RAULIN
(LISA - CNRS/IPSL, UPEC & Univ. Paris Diderot)



French activities in Adaptive Optics for the E-ELT
Michel Tallon
(CRAL - Centre de Recherche Astrophysique de Lyon)
The European Extremely Large Telescope relies on various new Adaptive Optics systems to reach its expected performances. These systems are complex and drive an intense activity in Europe, both for the telescope itself and for its instrumentation. I will review the current activities of the French High Angular Resolution community in this field.



CFHT Decade 4
Christian Veillet
(CFHT)
CFHT turned thirty in October of last year. In spite of its age and relatively modest size, CFHT is among the most productive facilities in today's astronomy, thanks on one hand to the caliber of its users, and on the other hand to a current suite of excellent instruments, an efficient queued service observing mode, and much interaction between the observatory and the PIs. With exciting new instruments under study or development, CFHT is in the process of defining a development plan, ``CFHT Decade 4'', covering the 2010-2020 period and beyond. This talk will be an opportunity to present the current status of this plan, seen from an observatory perspective, to the French community.




Sous-sections
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Samuel Boissier 2010-06-16