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2569745 
Journal Article 
Direct thermal imaging of circumstellar discs and exo-planets - art. no. 70142D 
Pantin, E; Siebenmorgen, R; Cavarroc, C; Sterzik, MF 
2008 
Unk 
Proceedings of SPIE
ISSN: 0277-786X
EISSN: 1996-756X 
PROCEEDINGS OF THE SOCIETY OF PHOTO-OPTICAL INSTRUMENTATION ENGINEERS (SPIE) 
7014 
D142-D142 
WOS:000259917700079 
The phase A study of a, mid infrared imager and spectrograph for the European Extremely Large Telescope (E-ELT), called METIS, was endorsed in May 2008.(1) Two key science drivers of METIS are: a) direct thermal imaging of exo-planets and b) characterization of circumstellar discs from the early proto-planetary to the late debris phase. Observations in the 10 mu m atmospheric window (N band) require a contrast ratio between stellar light and emitted photons from the exo-planet or the disc of similar to 10(5). At shorter wavelengths the contrast between star and reflected light from the planet-disc system exceeds greater than or similar to 10(7) posing technical challenges. By means of end-to-end detailed simulations we demonstrate that the superb spatial resolution of a 42m telescope in combination with stellar light rejection methods such as coronagraphic or differential imaging will allow detections at 10 mu m for a, solar type system down to a star-planet separation of 0.1 '' and a mass limit for irradiated planets of I Jupiter (M-.1) mass. In case of self-luminous planets observations are possible further out e.g. at the separation limit of JWST of similar to 0.7 '', METIS will detect planets greater than or similar to 5M(J). This allows to derive a, census of all such exo-planets by means of thermal imaging in a, volume limited sample of up to 6pc. In addition, METIS will provide the possibility to study the chemical composition of atmospheres of exo-planets using spectroscopy at moderate spectral resolution (Delta/Delta lambda similar to 100) for the brightest targets. Based on detailed performance and sensitivity estimates, we demonstrate that a mid-infrared instrument on an ELT is perfectly suited to observe gravitationally created structures such as gaps in proto- and post-planetary discs, in a complementary way to space missions (e.g. JWST, SOFIA) and ALMA which can only probe the cold dust emission further out. 
thermal infrared; mid infrared; exo-planet; proto-planetary discs; debris discs; coronagraphy