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Context. The James Webb Space Telescope will enable astronomers to obtain exoplanet spectra of unprecedented precision. The MIRI instrument especially may shed light on the nature of the cloud particles obscuring planetary transmission spectra in the optical and near-infrared. Aims. We provide self-consistent atmospheric models and synthetic JWST observations for prime exoplanet targets in order to identify spectral regions of interest and estimate the number of transits needed to distinguish between model setups. Methods. We select targets that span a wide range of planetary temperatures and surface gravities, ranging from super-Earths to giant planets, that have a high expected signal-to-noise ratio. For all targets, we vary the enrichment, C/O ratio, presence of optical absorbers (TiO/VO), and cloud treatment. We calculate atmospheric structures, emission, and transmission spectra for all targets and use a radiometric model to obtain simulated observations. Further, we analyze JWST's ability to distinguish between various scenarios. Results. We find that in very cloudy planets, such as GJ 1214b, less than ten transits with NIRSpec may be enough to reveal molecular features. Furthermore, the presence of small silicate grains in atmospheres of hot Jupiters may be detectable with a single JWST MIRI transit. For a more detailed characterization of such particles less than ten transits are necessary. Finally, we find that some of the hottest hot Jupiters are well fitted by models which neglect the redistribution of the insolation and harbor inversions, and that 1-4 eclipse measurements with NIRSpec are needed to distinguish between the inversion models.Conclusions. Wet thus demonstrate the capabilities of JWST for solving some of the most intriguing puzzles in current exoplanet atmospheric research. Further, by publishing all models calculated for this study we enable the community to carry out similar studies, as well as retrieval analyses for all planets included in our target list.

Abstract. High resolution, mid-infrared (MIR) images of nine nearby active galaxies are presented. The data were obtained with the TIMMI 2 instrument mounted at the ESO 3.6 m telescope using a set of N-band narrow filters. The resulting images have an angular resolution of 0.6 −1 . The MIR emission has been resolved in four galaxies: NGC 253, NGC 1365, NGC 1808 and NGC 7469. The images show a circumnuclear population of unknown MIR sources in NGC 1365 and NGC 1808, coincident with radio sources. These MIR/radio sources are interpreted in terms of embedded young star clusters. A high-resolution MIR map of NGC 253 is also presented, and enables the identification of a previously unknown MIR counterpart to the radio nucleus. Extended MIR emission is detected in NGC 7469, and concurs with previous observations in the NIR and radio. For this source, an interesting morphological difference between the 10.4 µm and the 11.9 µm emission is observed, suggesting the presence of a dust-rich micro-bar. Our MIR images of Circinus do not show resolved emission from the nucleus down to an angular scale of 0.5 . In the case of NGC 2992, an upper limit to the extended MIR emission can be set. We provide new MIR flux measurements for the unresolved AGN in NGC 5995, IZw1 and IIZw136.

MIRI (the Mid-Infrared Instrument for the James Webb Space Telescope (JWST)) operates from 5 to 28.5 µm and combines over this range: 1.) unprecedented sensitivity levels; 2.) sub-arcsec angular resolution; 3.) freedom from atmospheric interference; 4.) the inherent stability of observing in space; and -3 -5.) a suite of versatile capabilities including imaging, low and medium resolution spectroscopy (with an integral field unit), and coronagraphy. We illustrate the potential uses of this unique combination of capabilities with various science examples: 1.) imaging exoplanets; 2.) transit and eclipse spectroscopy of exoplanets; 3.) probing the first stages of star and planet formation, including identifying bioactive molecules; 4.) determining star formation rates and mass growth as galaxies are assembled; and 5.) characterizing the youngest massive galaxies.

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Abstract. SuperNova Remnants (SNR) have been extensively studied in radio, X-rays and optical, but barely in the InfraRed (IR). From IRAS observations, SNR are known to be IR emitters, but the origin of the emission is difficult to assess because of the limited angular and spectral resolution of IRAS observations. ISO follow-up observations of the Cassiopeia-A SNR have shown that the mid-IR radiation from this remnant was dominated by thermal emission from silicate condensates made from SN material. These condensates constitute a probe which can provide unique information about element mixing inside a SN. In this paper, we present ISOCAM observations of the three other young SNR's known in our galaxy: the Kepler SNR, the Tycho SNR and the Crab Nebula. The emission observed from the Kepler SNR is dominated by dust thermal emission. The dust at the origin of the IR emission is circumstellar, not from SN condensates. "Astronomical" silicates, collisionally heated to a temperature of 107 K, can account for both the mid-IR ISO data and the IRAS data. The IR emission from Tycho is probably also emitted by circumstellar or interstellar dust. In order to reproduce both the mid-IR ISO data and the IRAS data, a model with two dust components, one at a temperature of 107 K and the other at 55 K, is needed. The mid-IR emission from the Crab is dominated by synchrotron radiation; no dust is detected.

Given the forthcoming launch of the James Webb Space Telescope (JWST) which will allow observing exoplanet atmospheres with unprecedented signal-over-noise ratio, spectral coverage and spatial resolution, the uncertainties in the atmosphere modelling used to interpret the data need to be assessed. As the first step, we compare three independent 1D radiative-convective models: ATMO, Exo-REM and petitCODE. We identify differences in physical and chemical processes taken into account thanks to a benchmark protocol we developed. We study the impact of these differences on the analysis of observable spectra. We show the importance of selecting carefully relevant molecular linelists to compute the atmospheric opacity. Indeed, differences between spectra calculated with Hitran and ExoMol exceed the expected uncertainties of future JWST observations. We also show the limitation in the precision of the models due to uncertainties on alkali and molecule lineshape, which induce spectral effects also larger than the expected JWST uncertainties. We compare two chemical models, Exo-REM and Venot Chemical Code, which do not lead to significant differences in the emission or transmission spectra. We discuss the observational consequences of using equilibrium or out-of-equilibrium chemistry and the major impact of phosphine, detectable with the JWST.Each of the models has benefited from the benchmarking activity and has been updated. The protocol developed in this paper and the online results can constitute a test case for other models.

With a scheduled launch in 2018 October, the James Webb Space Telescope ( JWST) is expected to revolutionize the field of atmospheric characterization of exoplanets. The broad wavelength coverage and high sensitivity of its instruments will allow us to extract far more information from exoplanet spectra than what has been possible with current observations. In this paper, we investigate whether current retrieval methods will still be valid in the era of JWST, exploring common approximations used when retrieving transmission spectra of hot Jupiters. To assess biases, we use 1D photochemical models to simulate typical hot Jupiter cloud-free atmospheres and generate synthetic observations for a range of carbon-to-oxygen ratios. Then, we retrieve these spectra using TauREx, a Bayesian retrieval tool, using two methodologies: one assuming an isothermal atmosphere, and one assuming a parameterized temperature profile. Both methods assume constant-with-altitude abundances. We found that the isothermal approximation biases the retrieved parameters considerably, overestimating the abundances by about one order of magnitude. The retrieved abundances using the parameterized profile are usually within 1σ of the true state, and we found the retrieved uncertainties to be generally larger compared to the isothermal approximation. Interestingly, we found that by using the parameterized temperature profile we could place tight constraints on the temperature structure. This opens the possibility of characterizing the temperature profile of the terminator region of hot Jupiters. Lastly, we found that assuming a constant-with-altitude mixing ratio profile is a good approximation for most of the atmospheres under study.