INPhINIT Incoming PhD: "Unveiling exoplanets atmospheres with the James Webb Space Telescope"

The large number of exoplanets known to date (>4500) has showed us the rich diversity of both planets and planetary systems. The enormous jump, from knowing just our own Solar System to more than three thousand other systems discovered in only ~25 years, opened a new field of research and posed a major challenge: learning how planets form and how they evolve. To answer those questions it is pivotal to fully characterise them in a systematic way. A key part of such a characterisation process is the study of their atmospheres. Planetary atmospheres hold themselves compositional signatures left by their formation and migration histories, which makes them as cipher keys to understand planetary formation processes. In the past decade, important progress in the exo-atmospheric composition, temperature structure has been made, both from space (with the Spitzer Space telescope and the Hubble Space Telescope) and by using large ground-based telescopes. However, the next major step forward is expected to come from the James Webb Space Telescope (JWST) observations, to be launched very soon at the end of 2021. JWST will provide a major advantage: its high resolution, its near- and mid-infrared spectrometers, and its spectra not being contaminated by our atmosphere, are expected to provide unique data which will advance significantly our knowledge on exo-atmospheres. In particular the knowledge on their temperature structure, composition, clouds, and dynamics. The work proposed for this PhD position is set within this framework.
The main aim is to analyse JWST infrared and near-infrared data of the targeted exoplanets to derive their atmospheric properties (temperature, composition, winds, clouds, hazes, etc.). Among the targets we find a large variety, from hot gas giants to Neptunes, mini-Neptunes, super-Earth’s and terrestrial planets (https://www.stsci.edu/jwst/science-execution/approved-programs). Preference will be given to the targets of the Early Release Science (ERS) program. In order to carry out those tasks, several groups have already developed tools, which are openly available, e.g., Taurex3, Chimera, Nemesis, ARCIS, to cite a few.
Thus, one major goal of this work will be to retrieve the atmospheric parameters (mainly temperature and composition) of selected targets.
In addition to that, we also plan to make a unique contribution: all of the tools publicly available assume that the atmospheric infrared emission of exoplanets occurs under the conditions of Local Thermodynamics Equilibrium (or LTE). It is well known, though, that non-LTE is very important in the study of planetary atmospheres in our Solar System. Hence, we plan to develop a non-LTE general model capable of modelling the non-LTE infra-red emission of the most abundant molecules (H2O, CH4, CO and CO2) so far detected in exo-atmospheres, including hot-Jupiters, Neptunes, sub-Neptunes and Super-Earths. Once developed, we will apply it to analyse JWST data, in particular those of the hot-Jupiter HD 189733 b, for which there is controversy about whether the CH4 IR emission is LTE or not.
The Terrestrial-Planetary atmosphere group (GAPT) at the Instituto de Astrofísica de Andalucía-CSIC, a Severo Ochoa Centre of Excellence, has a long-recognised experience in the analysis of non-LTE infrared emission of planetary atmosphere taken by many satellite-borne spectrometers (http://gapt.iaa.es).