2025MNRAS.542.1873M

We present the results from the simulations of the atmospheres of hot-Jupiters HD 189733b, HD 209458b, and WASP-39b, assuming the presence of three different types of haze. Using a 3D general circulation model, the Unified Model, we capture the advection, settling, and radiative impact of Titan-, water-world-, and soot-like haze, with a particle radius of 1.5 nm. We show that the radiative impact of haze leads to drastic changes in the thermal structure and circulation in the atmosphere. We then show that in all our simulations, (1) the super-rotating jet largely determines the day-to-night haze distribution, (2) eddies drive the latitudinal haze distribution, and (3) the divergent and eddy component of the wind control the finer structure of the haze distribution. We further show that the stronger the absorption strength of the haze, the stronger the super-rotating jet, lesser the difference of the day-to-night haze distribution, and larger the transit depth in the synthetic transmission spectrum. We also demonstrate that the presence of such small hazes could result in a stronger haze opacity over the morning terminator in all three planets. This could lead to an observable terminator asymmetry in WASP-39b, with the morning terminator presenting a larger transit depth than the evening terminator. This work suggests that, although it might not be a typical detection feature for hot Jupiters, an observed increase in transit depth over the morning terminator across the ultraviolet and optical wavelength regime could serve as a strong indicator of the presence of haze.