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Accueil > Séminaires > Archive des séminaires d’Utinam > Archive des séminaires d’astrophysique (jusqu’en 2011) > 2011

Gravitation Astrometric Measurement Experiment

par Edith Burgey -

Le jeudi 16 juin à 14h en salle de conférences de l’observatoire,

par Mario Gai, Professeur à l’Instituto Nazionale di Astrofisica, Turin

GAME (Gravitation Astrometric Measurement Experiment) is a mission concept taking advantage of proven astrometric and coronagraphic techniques (inherited from e.g. Gaia and Solar Orbiter) for high precision measurements of interest to Fundamental Physics, and in particular the Υ and β parameter of the Parameterized Post-Newtonian formulation of gravitation theories extending the General Relativity. A space based telescope, looking close to the Solar limb thanks to coronagraphic techniques, may implement astrometric measurements similar to those performed in the solar eclipse of 1919, when Dyson, Eddington and Davidson measured for the first time the gravitational bending of light. Also, high precision determination of Mercury’s perihelion precession is planned, implementing in the same experiment two of the classical tests on General Relativity.
The final accuracy of GAME is expected to reach the 10-8 level on Υ and the 10-5 level on β within the framework of a medium class space mission, thus providing crucial contributions to our understanding of gravity physics, cosmology and the Universe evolution at a fundamental level.
The GAME capabilities may be used to advantage of a wider science case, ranging from stellar astrophysics to Solar system dynamics. In the hot field of extra-solar planetary systems, GAME is able to provide microarcsec astrometry and time resolved photometry for a large set of objects, known by Radial Velocity but not observable by Gaia or Corot, thus yielding solutions for multiplicity, mass and orbital parameters.
The GAME science case and implementation concept are described. The GAME principle is based on the differential astrometric signature on the positions of stars and planets. The instrument concept ensures rejection of the systematic errors to within a factor 2 of the photon noise limit.