Exoplanetary atmospheric properties with MIRI

This wavelength range is key for both determining the bolometric luminosity of the cool known exoplanets and for accessing the strongest ammonia bands. In conjunction with shorter wavelength observations, MIRI will enable a more accurate characterization of the exoplanetary atmospheric properties.

Here we consider a subsample of the currently known exoplanets detected by direct imaging, and we discuss their detectability with MIRI, either using the coronagraphic or the spectroscopic modes. By using the Exo-REM atmosphere model, we calculate the mid-infrared emission spectra of 14 exoplanets, and we simulate MIRI coronagraphic or spectroscopic observations. Specifically, we analyze four coronagraphic observational setups, which depend on (i) the target-star and reference-star offset (0, 3, 14 mas), (ii) the wavefront-error (130, 204 nm root mean square), and (iii) the telescope jitter amplitude (1.6, 7 mas).