http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/index.php News du Sap http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3281 Thu, 11 Apr 2013 00:00:00 GMT An international collaboration of astrophysicists, led by Martin Kilbinger from the Astrophysics Division - AIM Laboratory AIM at CEA Saclay-Irfu and the Institute of Astrophysics Paris, has obtained the largest survey of galaxy images that are deformed by gravitation. More than 4.2 million galaxies have been observed during more than 500 nights at the Canada-France Hawaii Telescope (CFHT) with the camera MegaCam, built at the CEA. The fine analysis of these images is the goal of the CFHTLenS project [1]. The very small distortions of galaxy images allowed to determine the fraction of dark matter and dark energy in a slice of the Universe between 2.4 and 8.8 billion years in the past, with a unprecedented level of precision. These results are complementary to those recently obtained by the Planck satellite at great distances from the analysis of the diffuse microwave background. This work is in press in the journal Monthly Notices of the Royal Astronomical Society (2013). http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3281 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3250 Fri, 07 Dec 2012 00:00:00 GMT The European Southern Observatory (ESO) Council at its meeting at ESO's Headquarters in Garching, Germany on 4 December 2012 has given full approval for the start of the European Extremely Large Telescope (E-ELT) programme. With its 39,3 m diametre mirror, E-ELT will be the world largest ground-based telescope for visible and infrared observations. Four to five times bigger that the present most-advanced instruments, it will collect 15 times more light. Its size is also larger than the other competing installations the « Thirty-Meter Telescope » and the « Giant Magellan Telescope ». The vote of France has allowed to reach the two-third majority needed for the launch of the program. Within a consortium of other European laboratories, the CEA (Astrophysical Division - IRFU) is involved in the buiding of METIS, a spectro-imager operating in the infrared that will be one of the major instruments at the focus of the new giant telescope. Read more in : Le télescope européen géant E-ELT définitivement accepté (in French) http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3250 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3241 Wed, 28 Nov 2012 00:00:00 GMT Two scientists from the Université Nice Sophia Antipolis - Observatoire de la Côte d’Azur and from the Université Paris Diderot and CEA, have just proposed the first model to explain the origin of most of the regular satellites in our solar system. First proposed in 2010 to explain the repartition of the moons around the planet Saturn, this model is now extended to reproduce the distribution of the numerous satellites around the other giant gazeous planets (Jupiter, Neptune,…) and could as well explain the formation of satellites around the "rocky planets (Earth, Pluton,…). For all these planets, their moons may have formed from rings of matter that do not exist anymore today. These results are crucial to understand the universal laws that lead to the apparition of moons around planets. They are published in the last issue of the Science magazine (30 Novembre 2012). http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3241 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3231 Mon, 05 Nov 2012 00:00:00 GMT An international team of astrophysicists, including Samar Safi-Harb and Gilles Ferrand at the University of Manitoba (Canada) and Anne Decourchelle from the Astrophysical Department-AIM Laboratory (CEA Saclay - France), has produced the first 3D simulations of supernova remnants (SNRs) showing the effect of particle acceleration at the wave fronts generated by these powerful X-ray sources in our galaxy. The research is published in the last issue of the Astrophysical Journal.   http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3231 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3245 Tue, 09 Oct 2012 00:00:00 GMT Using the European X-ray astronomy satellite XMM-Newton [1], researchers from CNRS [2] and CEA [3] have discovered a new source of cosmic rays. In the vicinity of the remarkable Arches cluster, near the center of the Milky Way, these particles are accelerated in the shock wave generated by tens of thousands of young stars moving at a speed of around 700,000 km/h. These cosmic rays produce a characteristic X-ray emission by interacting with the atoms in the surrounding gas. Their origin differs from that of the cosmic rays discovered exactly a hundred years ago by Victor Hess, which originate in the explosions of supernovae. The findings are published in the October issue of the  Astronomy & Astrophysics journal.   http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3245 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3195 Fri, 06 Jul 2012 00:00:00 GMT A team led by Philippe André du Service d'Astrophysique-Laboratoire AIM du CEA-Irfu has just uncovered the very first stage of the formation  of a brown dwarf, one of these tiny stars with a mass just above the planets. Several hundreds brown dwarfs have already been detected in the galaxy but up to now it was impossible to observe their formation. Thanks to the great interferometer of IRAM (Institute de Radioastronomie Millimétrique), the scientists have located a compact condensation of gas and dust with a temperature of only 10 degrees above the absolute zero and a mass approximatively 2% the solar mass. These characteristics are exactly what expected to give birth to a brown dwarf. The discovery of this first proto brown dwarf is published in the Science magazine of July 6th, 2012   For a more detailed account, see the French version. http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3195 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3196 Thu, 05 Jul 2012 00:00:00 GMT Sporadic ejections of matter are observed in the form of radio jets from supermassive black holes in active galaxies as well as from galactic binary systems hosting a black hole of several solar masses. Do these observations indicate that jet formation is a universal property of black holes, regardless of their mass? The detection, for the first time, a transient radio jet from an intermediate-mass black hole by an international collaboration led by two French teams (IRAP in Toulouse and Service d'Astrophysique-Laboratoire AIM from CEA-Irfu at Saclay) finally settles the debate. The observations of the source HLX-1, using the ATCA radio telescope in Australia, have also helped to constrain the black hole mass to be between 9000 and 90,000 solar masses. This result, published in Science Express on 2012 July 5, provides a bridge between the two extremes of the population of black holes. http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3196 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3157 Fri, 03 Feb 2012 00:00:00 GMT The explosive death of massive stars begins with the collapse of their iron core which gives birth to a neutron star. Despite spherical initial conditions, this explosion can kick the neutron star several hundred kilometers per second. Exclusively studied by numerical simulations so far, the hydrodynamic instability responsible for this asymmetry is revealed here in a simple experiment. Making use of the analogy between surface waves in water and shocks in a compressible gas, it describes the mechanism contributing to the neutron star kick and spin at birth. The work led by Thierry Foglizzo at the Astrophysical Department - AIM laboratory (CEA/Irfu - CNRS - University Paris Diderot) and co-workers is an original combination of theory, numerical simulations and experimental analogy addressing a complex astrophysical phenomenon. These results are published in Physical Review Letters, February 3, 2012.   http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3157 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3026 Wed, 30 Mar 2011 00:00:00 GMT Thanks to the data of the NASA  Kepler satellite, an international team including Rafael Garcia of the Astrophysical Department at CEA-Irfu [1], succesfully probe the heart of hundreds of giant stars for the first time. The researchers used stellar seismology to analyze very small oscillations in surface brightness to infer the characteristics of the heart of the stars. In the large sample studied, they have managed to distinguish where the nuclear fusion reactions take place, in the core of the stars or in a surrounding shell. This is a major discovery for the understanding of the stars because so far nothing helped the astronomers to isolate these evolutionary stages corresponding to a different stage in the life of a star. The results are published in the journal Nature of March 31, 2011.   The concert of red giants (mp3) Listen to the vibrations of giant stars translated into audible sounds according to their actual frequencies: listen to three stars of increasing size [1'00], Crédits Daniel Huber (Univ. Sydney 2011) http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3026 http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3029 Sat, 29 Jan 2011 00:00:00 GMT An international team, including scientists from the Astrophysics Department-AIM and the Particle Physics Department of CEA-Irfu, has just used the Planck satellite to discover galaxy clusters with characteristics that were previously unknown. These clusters, which contain up to a thousand galaxies, are the largest structures in the Universe. Many of them are located very far away from us, and we still know relatively little about them. Astrophysicists were able to detect the new clusters thanks to the imprint left in the background radiation of the universe by the hot gas from the clusters. Of the 189 clusters detected by Planck at distances from 1 to 5 billion light-years, 20 were previously unknown. Thanks to a joint program with the XMMNewton x-ray satellite, some of these new clusters could be observed, revealing weaker luminosity and a highly perturbed gas distribution. These must therefore be clusters with different characteristics.These results were presented at a scientific colloquium on results from the Planck satellite, held from 10th to 14th January 2011 in Paris. They were published in a special issue of Astronomy & Astrophysics. For a more detailed account, see also the French version. http://irfu.cea.fr/Sap/en/Phocea/Vie_des_labos/Ast/ast.php?t=actu&id_ast=3029