Colloquium: Atmospheric winds of hot exoplanets in interaction with stellar winds
Among very diverse planetary populations, close orbiting hot exoplanets possess a unique feature of hydrodynamic outflow of upper atmospheres. This phenomenon was revealed for a number of hot Jupiters and warm Neptunes via observations of transit absorption in VUV lines of such elements as H, He, C, O, Mg, Si. The multicomponent and partially ionized atmospheric material overflowing with a supersonic velocity the Roche lobe collides with the stellar wind plasma. This interaction principally differs from the processes in tenuous planetary exospheres in the Solar system. The escape of upper atmospheres of hot exoplanets is a complex phenomenon, and quantitative interpretation of observational data requires numerical simulations. The comparison of spectrally resolved transit measurements of particular exoplanets and 3D simulations of their dynamical environments gives a tantalizing evidence of planetary and stellar winds interaction, enabling to draw important conclusions about both the atmosphere of an exoplanet and the parameters of the stellar wind plasma. Fast increase of quality and amount of observations, new instruments, new approaches to the probing of planetary winds, including the new spectral windows, multi-spectral and multi-instrumental observations of targets require further development of the modeling tools capable of complex simulation and interpretation of all available observations.
In the presentation we describe a global 3D multi-fluid aeronomic MHD model, which is developed in cooperation of Institute of Laser Physics SB RAS, Novosibirsk and Space Research Institute, Graz. It was applied for a number of specific exoplanets enabling to infer constrains on atmospheric and stellar parameters.
recording: www.youtubee.com/watch