Seminario DAS: "Atmospheric Diversity of Exoplanets with the VLT and ELT"

Speaker: Dr. Paulina Palma-Bifani
Affiliation:  LIRA, Observatoire de Paris

Abstract: The past decade has seen a revolution in exoplanet spectroscopy, revealing an extraordinary diversity of atmospheres across directly imaged planets and brown dwarfs. However, most interpretations still rely on one-dimensional, vertically uniform models, even though real atmospheres are inherently three-dimensional and time-variable. In this talk, I will present results from ForMoSA, a forward-modeling framework that takes as input self-consistent atmospheric models and observed spectra of exoplanets to retrieve the physical properties of these objects. I will discuss key findings on benchmark systems such as AB Pic b, β Pictoris b, and AF Lep b, and highlight the limitations of this approach in explaining features like thermal inversions and patchy cloud patterns. To address these interesting challenges, I am developing Exo-OPT, an optimal-estimation retrieval framework that bridges ForMoSA and Exo-k to explore multidimensional atmospheric states iteratively. This methodology enables the modeling of thermal inversions potentially caused by auroral heating (as observed with JWST) and longitudinal chemical variations driven by cloud structures (detectable with VLT/CRIRES data). These effects are only beginning to be observed but will soon be routinely accessible with ELT-class spectrographs such as MICADO, making this work a timely step toward interpreting the complex, four-dimensional nature of exoplanet atmospheres.