Stellar wind effect on the atmospheric escape of hot Jupiters

Abstract:

Since the first discovery in 1995, many hot Jupiters have been detected. It is thought that the atmosphere of hot Jupiters escapes owing to photoheating by the Extreme-ultraviolet (EUV; >13.6eV) radiation from the host star. The atmospheric escape can change the evolution of close-in giant planets. Using 1D radiation hydrodynamics simulations, Vidotto & Cleary (2020) show that the strong stellar wind can confine the atmosphere within a compact region and reduces the mass-loss rates. However, the multi-dimensional effects remain unclear. Multidimensional hydrodynamics simulations are unique tool to study important factors for the planetary evolution, such as the mass-loss rates and angular momentum loss. We run 2D hydrodynamical simulations including radiative transfer for EUV and non-equilibrium chemistry. We find that the stellar wind confines the atmosphere and the mass-loss rate becomes about 30% smaller when the stellar wind is ten times stronger than the sun. In case where the stellar wind is 1000 times stronger than the sun, there is almost no mass loss due to EUV because of the atmospheric confinement. We also find that in the case of strong EUV like young stars, the ram pressure of the escaping atmosphere is larger, and the effect of the stellar wind is smaller. Our multidimensional simulations reveal that the escaping atmosphere from the day side is pushed toward the night-side by the stellar wind, and the flow structure changes.Taking into account the stellar evolution, we discuss the long-term evolution of the mass-loss rates and the effect of the stellar wind on the planetary orbital evolution over stellar lifetimes.