Program: GS-2024A-Q-138

Owing to their high equilibrium temperatures (>2000K), short orbital periods, and strong stellar irradiation levels, tidally locked ultra-hot Jupiters are unique laboratories within which to study a range of physical, chemical, and dynamical processes in giant exoplanet atmospheres. Under these extreme conditions, their highly irradiated permanent daysides can reach temperatures upwards of 3000K and exhibit different atmospheric chemistry from their cooler, permanent nightsides. In particular, molecules such as water are expected to dissociate in their dayside atmospheres, many atomic elements are found in their ionized states, and temperature-pressure (T-P) profiles often exhibit thermal inversions. High-resolution spectroscopy of day-side (i.e., pre- and post-eclipse) orbital phases can help constrain these thermal structures as well as the dayside chemistry. We propose a comparative study of the dayside atmospheres of 4 ultra-hot Jupiters with GHOST at Gemini South. We will investigate the chemical compositions and thermal structures of these planets as a function of their temperatures, surface gravities, and host star properties. Our survey will help inform our understanding of extreme physics and chemistry in exoplanet atmospheres.