Transition from super-alfvenic to sub-alfvenic stellar wind flow passing by an exoplanet, using the example of HD 209458b

Depending on the distance of the exoplanet from the central star and on the properties of this star, different regimes of stellar wind flow around it arise. If the exoplanet is at a distance up to the Alfven radius at which the wind speed is equal to the Alfven speed, or the Alfven Mach number MA = 1, then the exoplanet generates Alfven wings. If it is located beyond the Alfven radius, a comet-like magnetosphere appears, like that of the planets of the Solar System. The paper examines how the transition from one flow regime to another can be described on the base of a paraboloid model of the magnetospheric magnetic field using the example of exoplanet HD 209458b.