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Paper: Three-dimensional Gas Dynamic Simulations of the Interaction Between the Stellar Wind and Non-magnetized Exoplanets
Volume: 474, Numerical Modeling of Space Plasma Flows (ASTRONUM2012)
Page: 41
Authors: Bisikalo, D. V.; Kaygorodov, P. V.; Ionov, D. E.
Abstract: The investigation of the flow structure in systems consisting of a star and orbiting exoplanet is one of the most interesting problems in modern astronomy. The results of the observations, carried out with modern ground- and space-based instruments show quite complex flow patterns in the systems where planets are close enough to their host stars to have supersonic orbital velocities. We present the results of the numerical simulations of gas dynamics in the WASP-12 system. In this system, the atmosphere of the WASP-12b planet overfills its Roche lobe. This results in the formation of an intensive gas outflow in the form of a collimated stream issuing from the L1 point and a wider flow through the vicinity of the L2 point. The interaction of the planet's gaseous envelope with the stellar wind causes the formation of a double-humped bow-shock and a region of the turbulent mixing near the stream from the L1 point. Analyzing the results of the simulations, we can conclude that the interaction with the stellar wind gas breaks the propagation of the flows from L1 and L2 and the bow-shock encloses the gas envelope of the planet (quasi-atmosphere) that is extended far beyond the Roche lobe. The complex structure of the gas flow behind the bow shock contributes to the formation of complex-shaped absorption lines, observed during the planet transit. The observations of these lines can become a key in the investigations of physical processes in atmospheres of “hot Jupiters.” The position of the bow shock, found in the simulations, allows us to explain the occurrence of the observed early-ingress in this system.
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