AERONOMIC MODEL OF HYDROGEN-HELIUM UPPER ATMOSPHERES OF HOT GIANT EXOPLANETS

Abstract

The paper presents 1D aeronomic model of hydrogen-helium upper atmospheres of hot giant exoplanets based on the approximation of single-fluid multicomponent hydrodynamics. Chemical reactions and heating-cooling processes are taken into account. Typical hot Jupiter and warm Neptune are considered as an example of the application of the model. Calculations were carried out for various values of gas pressure at the photometric radius of the planet. In the solutions obtained, a transonic planetary wind is formed, leading to a hydrodynamic outflow of the atmosphere with mass loss rates of the order of \(3.5 \times {{10}^{{10}}}\) g/s for hot Jupiter and \(3.7 \times {{10}^{9}}\) g/s for warm Neptune. At the same time, the outer layers of the atmosphere of hot Jupiter are completely ionized, while the atmosphere of warm Neptune mainly consists of neutral gas. In some variants of the hot Jupiter model, instability develops in the deep layers of the atmosphere, which can lead to the formation of a specific cloud layer.