Instrument Concept And Science Case Of The Mid-Ir E-Elt Imager And Spectrograph Metis

METIS is the 'Mid-infrared ELT Imager and Spectrograph', the only planned thermal/mid-IR instrument for the E-ELT. METIS will provide diffraction limited imaging in the atmospheric L/M and N-band from 3 - 14 mu m over an 18 '' x 18 '' field of view (FOV). The imager also includes high contrast coronagraphy and low-resolution (900 <= R <= 5000) long slit spectroscopy and polarimetry. In addition, an IFU fed, high resolution spectrograph at L/M band will provide a spectral resolution of R similar to 100,000 over a 0.4 '' x 1.5 '' FOV. The adaptive optics (AO) system is relatively simple, and METIS can reach its full performance with the adaptive correction provided by the telescope - and occasionally even under seeing limited conditions. On a 42m ELT, METIS will provide state-of-the-art mid-IR performance from the ground. The science case for METIS is based on proto-planetary disks, characterization of exoplanets, formation of our Solar System, growth of supermassive black holes, and the dynamics of high-z galaxies. With the focus on highest angular resolution and highest spectral resolution, METIS is highly complementary to JWST and ALMA. This paper summarizes the science case for METIS, and describes the instrument concept, performance and operational aspects.