Hot Jupiters have been considered as natural candidates to harbour intense magnetic fields, both due to their large masses which might empower a larger internal dynamo, and, possibly, due to their high energy budgets coming from irradiation. In this talk we focus on the latter aspect and perform MHD simulations of a narrow day-side atmospheric column of ultra-hot Jupiters, suitable for very high local temperatures (T ≳ 3000 K). Due to the high conductivity in this regime, the primary influence is the winding of the magnetic field caused by the intense zonal winds. In our study, we include a forcing that mimics the wind profiles observed in GCMs near the sub-stellar point. As a result, the shear layer generates a toroidal magnetic field, locally reaching few kG, which is supported by meridional currents.

Over the past two decades, a coherent picture has emerged for the atmospheric dynamics of hot Jupiters from both three-dimensional general circulation models (GCMs) and observations. The standard model of hot Jupiter atmospheric circulation consists of a strong superrotating equatorial jet driven by a planetary-scale standing wave pattern triggered by day-to-night irradiation contrasts. This circulation pattern is relatively stable, with time-variability due to dynamics potentially detectable yet only at the few percent level in temperature. Conversely, current models for the atmospheric dynamics of sub-Neptunes and rocky planets often display hysteresis and time-variability, the former of which may be especially common at the boundaries between dynamical regimes. In this work, I explore the extent to which hot Jupiter circulation is independent of initial temperature and wind conditions. I find that the resulting dynamics is ubiquitously insensitive to the initial conditions, implying that the current paradigm of hot Jupiter circulation is robust.