This is the second paper in a series where we build a self-consistent model to simulate the mass loss process of a close orbit magnetized giant exoplanet, so-called Hot Jupiter (HJ). In this paper we generalize the hydrodynamic (HD) model of a HJ's expanding hydrogen atmosphere, proposed in the first paper (Shaikhislamov et al. 2014), to include the effects of intrinsic planetary magnetic field. The proposed self-consistent axisymmetric 2D MHD model incorporates radiative heating and ionization of the atmospheric gas, basic hydrogen chemistry for the appropriate account of major species comprising HJ's upper atmosphere and related radiative energy deposition, as well as H 3 + and Lyα cooling processes. The model also takes into account a realistic solar-type XUV spectrum for calculation of intensity and column density distribution of the radiative energy input, as well as gravitational and rotational forces acting in a tidally locked planet-star system. An interaction between the expanding atmospheric plasma and an intrinsic planetary magnetic dipole field leads to the formation of a current-carrying magnetodisk which plays an important role for topology and scaling of the planetary magnetosphere. A cyclic character of the magnetodisk behavior, comprised of consequent phases of the disk formation followed by the magnetic reconnection with the ejection of a ring-type plasmoid, has been discovered and investigated. We found that the mass loss rate of an analog of HD209458b planet is weakly affected by the equatorial surface field <0.3 G, but is suppressed by an order of magnitude at the field of 1 G.

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In the present series of papers we propose a consistent description of the mass loss process.To study the effects of intrinsic magnetic field of a close-orbit giant exoplanet (so-called Hot Jupiter) on the atmospheric material escape and formation of planetary inner magnetosphere in a comprehensive way, we start with a hydrodynamic model of an upper atmosphere expansion presented in this paper. While considering a simple hydrogen atmosphere model, we focus on selfconsistent inclusion of the effects of radiative heating and ionization of the atmospheric gas with its consequent expansion in the outer space. Primary attention is paid to investigation of the role of specific conditions at the inner and outer boundaries of the simulation domain, under which different regimes of material escape (free-and restricted-flow) are formed. Comparative study of different processes, such as XUV heating, material ionization and recombination,  3

The interaction of escaping upper atmosphere of a hydrogen rich non-magnetized analog of HD209458b with a stellar wind of its host G-type star at different orbital distances is simulated with a 2D axisymmetric multi-fluid hydrodynamic model. A realistic sun-like spectrum of XUV radiation which ionizes and heats the planetary atmosphere, hydrogen photo-chemistry, as well as stellar-planetary tidal interaction are taken into account to generate self-consistently an atmospheric hydrodynamic outflow. Two different regimes of the planetary and stellar winds interaction have been modelled. These are: 1) the "captured by the star" regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe towards the star, and 2) the "blown by the wind" regime, when sufficiently strong stellar wind confines the escaping planetary atmosphere and channels it into the tail. The model simulates in details the hydrodynamic interaction between the planetary atoms, protons and the stellar wind, as well as the production of energetic neutral atoms (ENAs) around the planet due to charge-exchange between planetary atoms and stellar protons. The revealed location and shape of the ENA cloud either as a paraboloid shell between ionopause and bowshock (for the "blown by the wind" regime), or a turbulent layer at the contact boundary between the planetary stream and stellar wind (for the "captured by the star" regime) are of importance for the interpretation of Lyα absorption features in exoplanetary transit spectra and characterization of the plasma environments.

To shed more light on the nature of the observed Lyα absorption during transits of HD 209458b and to quantify the major mechanisms responsible for the production of fast hydrogen atoms (the so-called energetic neutral atoms, ENAs) around the planet, 2D hydrodynamic multifluid modeling of the expanding planetary upper atmosphere, which is driven by stellar XUV, and its interaction with the stellar wind has been performed. The model selfconsistently describes the escaping planetary wind, taking into account the generation of ENAs due to particle acceleration by the radiation pressure and by the charge exchange between the stellar wind protons and planetary atoms. The calculations in a wide range of stellar wind parameters and XUV flux values showed that under typical Sun-like star conditions, the amount of generated ENAs is too small, and the observed absorption at the level of 6%-8% can be attributed only to the non-resonant natural line broadening. For lower XUV fluxes, e.g., during the activity minima, the number of planetary atoms that survive photoionization and give rise to ENAs increases, resulting in up to 10%-15% absorption at the blue wing of the Lyα line, caused by resonant thermal line broadening. A similar asymmetric absorption can be seen under the conditions realized during coronal mass ejections, when sufficiently high stellar wind pressure confines the escaping planetary material within a kind of bowshock around the planet. It was found that the radiation pressure in all considered cases has a negligible contribution to the production of ENAs and the corresponding absorption.