Résumé / Abstract Seminaire_IAP
« SPHERE: a Planet Finder instrument for the Very Large Telescope »

Jean-Luc Beuzit
Lab. Astroph. Grenoble (LAOG) (Grenoble, France)

Direct detection and spectral characterization of extra-solar planets is one of the most exciting but also one of the most challenging areas in modern astronomy. The challenge consists in the very large contrast between the host star and the planet, larger than 12.5 magnitudes (or 10^5 in flux ratio), at very small angular separations, typically inside the seeing halo. The whole design of a "Planet Finder" instrument is therefore optimised towards reaching the highest contrast in a limited field of view and at short distances from the central star. Both evolved and young planetary systems can be detected, respectively through their reflected light (mostly by visible differential polarimetry) and through the intrinsic planet emission (using IR differential imaging and integral field spectroscopy).
For its second-generation instrumentation on the VLT, ESO has supported two phase A studies for such a dedicated instrument. Based on the results of these two studies, a unique instrument, SPHERE, is now considered for first light in 2011, including a powerful extreme adaptive optics system, various coronagraphs, an infrared differential imaging camera, an infrared integral field spectrograph and a visible differential polarimeter. Both components of the near-infrared arm of SPHERE will provide complementary detection capabilities and characterization potential, in terms of field of view, contrast, and spectral domain. The SPHERE project has successfully passed its Preliminary Design Review in September 2007 and is now in its final design phase. I will summarize the science objectives, describe the proposed conceptual design, discuss the main limitations and corresponding instrumental issues of such a system and finally review the expected performance of the proposed instrument.
vendredi 21 mars 2008 - 11:00
Salle des séminaires Évry Schatzman, Institut d'Astrophysique de Paris
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