The close location of many known exoplanets to their host stars leads to intensive heating and ionization of their upper atmospheres by the stellar X-ray and EUV radiation. As a result, the partially ionized atmospheric material expands and forms a kind of escaping planetary wind. At higher altitudes, the planetary wind, driven by the gravitational, centrifugal, MHD, and stellar radiation pressure forces, interacts with the entire stellar wind and is either blown away, or accreted on the star. This constitutes the essence of the planetary mass loss. The escaping planetary wind, being often a supersonic one, affects the entire stellar system and results in many still unexplored processes.
In accordance with its research program, the project was aimed at the investigation and characterization of different regimes of exoplanetary and stellar winds interaction, paying attention to their observational manifestations and the role of planetary magnetic field. Special focus was made on the simulation of complex dynamic environments of exoplanets, and interpretation of the real transmission spectroscopy data acquired in course of the project by partner astronomer teams.
To achieve the project goals, several numerical codes were developed and upgraded. Based on the chemical code CHROME, the model of a multicomponent planetary atmosphere has been created, applicable to a wide range of exoplanets. It was used to calculate chemical reactions in the elaborated hydrodynamic and MHD models of the escaping exoplanetary atmospheres, which were extended to simulate the dynamics of their components (e.g., H, H2, H3, He, C, O, Mg, Si, N2, CO2) and corresponding ions, taking into account the whole range of plasma photo-chemistry reactions, particle collisions, and basic driving forces. The original 2D models were upgraded in the course of the project to global 3D numerical codes, which for the first time enabled a self-consistent simulation of the stellar winds and aeronomy of the expanding upper atmospheres of exoplanets in their mutual interaction. The developed models were used for the simulation of mass loss and interpretation of the in-transit spectral absorption measured in various lines for the exoplanets HD 209458b (Lyα, OI, CII, SiI, MgI, MgII); WASP-12b (MgII); WASP-107b (HeI); π Men c (Lyα); GJ3470b (Lyα, HeI), and GJ436b (Lyα). Besides of that, to study the atmosphere evolution of Earth-like planets in the vicinity of active stars, the multi-component 1D models of N2- and CO2-dominated atmospheres were elaborated (Kompot Code). As an additional direction, the project developed the methods for the analysis of border regions of the transit light curves, provided by the Kepler Space Telescope, and in this way enabled the probing of dusty structures possibly present in the immediate vicinity of some exoplanets.