Hot Jupiters and Gaseous Planets

Hot Jupiters are giant planets orbiting extremely close to their stars. While originally not predicted to exist, they have been central to exoplanet atmospheric research since the field’s beginnings. Their high temperatures, inflated atmospheres, and strong irradiation also make them ideal natural laboratories for testing theories of atmospheric physics and chemistry under extreme conditions. Because they produce strong and frequent transit and eclipse signals, Hot Jupiters are among the best-characterized exoplanets to date. They provide insights into the diversity of planetary atmospheres beyond our Solar System.

For our group, Hot Jupiters serve as benchmark targets for developing and validating advanced modeling and retrieval frameworks. Their rich spectra - obtained from missions like Hubble, Spitzer, and JWST - enable us to rigorously test radiative transfer models, chemistry, aerosols, and dynamical models against real data. By comparing retrieval results with forward models that incorporate processes like radiative forcing, chemistry, heat redistribution, and atmospheric dynamics, we refine our understanding of how complex atmospheric processes interact, and we improve predictions for future missions like Ariel.

In particular, our group has developed pionering retrieval techniques to exploit the spectroscopic phase-curves of Hot jupiters. Because Hot jupiters are tidally locked, their atmospheres experiences extreme conditions, with temperature gradients between their permanent dayside and permanent nightside reaching thousands of degrees. This drives extreme dynamics that can be captured in phase-curves. Specifically, phase-curve consists in observing the planet along an entire orbite, essentially scanning its 3D thermal emission to construct maps of its atmospheric properties. The information from these data are crutial to providing initial conditions, forcing, and benchmarks to atmospheric dynamics models.

Beyond their role as testbeds, Hot Jupiters are also key to addressing fundamental questions in planetary formation and evolution. Their inflated radii, orbital configuration, and observed atmospheric compositions provide clues about their formation and evolution. By studying these planets in detail, and importantly searching for correlations in their observed properties, we can understand their origins and extend our formation models to the solar system, and to smaller, cooler, and more complex worlds. In this sense, Hot Jupiter are the cornerstone of our group’s effort to bridge detailed atmospheric modeling with large-scale statistical insights into the nature of exoplanets.