Final Report

• Overall scientific concept and goals:

          A distinctive feature of hot close-orbit exoplanets consists in the expansion and outflow of their upper atmospheres, ionized and heated by the UV and soft X-ray radiation of the parent stars. The outflowing partially ionized atmospheric material, interacting with the surrounding stellar wind plasma, forms a dynamical plasmasphere around the planet. Such plasmaspheres are a new object for astrophysics, which involves the photochemistry and collisional hydrodynamics of the planetary gas, as well as the specifics of the fast and collisionless stellar wind. The study and detailed modelling of the dynamics and structure of plasmaspheres of hot exoplanets is of high interest for the interpretation of the measured stellar radiation spectra absorbed by transiting exoplanets, as it significantly expands the possibilities for probing of a variety of physical and chemical characteristics of both the planets and their stars. Since 2003, the modeling of physical processes related with the mass loss of upper exoplanetary atmospheres passed a long way of development, from simple quasi-empirical analytical estimations to complex kinetic and (magneto)hydrodynamic numerical  codes. The achieved level of modelling enables interpretation of the measured transit absorption in the lines of various elements and characterizing of the composition and dynamics of the escaping atmospheres of close-orbit ‘hot Jupiters and Neptunes’. At the same time, while the task of revealing of atmospheric composition is solved relatively straight forward - by the detection of particular spectral lines, which change their intensity during the planet transits, the characterization of escaping atmospheric flows and quantifying of the abundances of detected elements depend on the quality and capacity of the applied computational models and the adopted assumptions. On the other hand, the ability of numerical model to reproduce observations serves as verification of the model itself, validating its scientific consistency.

          The project was aimed at the investigation and characterization of different regimes of the exoplanetary and stellar winds interaction, paying attention to their observational manifestations and the possible 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. Usually, to fit the numerical simulations to observations, different artificial assumptions are made either regarding the stellar radiation flux, which to significant extend is a measurable parameter constrained by the nature of the star, or about the specifics of interaction of the stellar and planetary material flows, as well as on the role of different physical effects to be included in the modelling. In contrast, the global fully self-consistent 3D multi-fluid model, developed in the project, which simulates the escaping atmosphere of hot close-orbit exoplanets and the surrounding stellar wind, is free of such assumptions.

• Were there changes in research orientation between the beginning and the end of the project? If so, what form did the change take, what effect did it have on the work?

          The research plan initially described in the proposal has been extended towards more extensive simulation and interpretation of the newly obtained observational data (HST, WASP) regarding the transit absorption of different exoplanets and probing of their atmospheric composition as well as the structure of the escaping planetary wind flows. As a result, the modelling and visualization tools were developed to simulate and analyze the dynamics of major atmospheric elements and their ions, taking into account the whole range of plasma photo-chemistry reactions, particle collisions, and basic driving forces. The extended scope of studies included the simulation of mass loss and interpretation of the measured in-transit spectral absorption 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, the performed research revealed the limitations of the initially planned 2D model for the considered exoplanets. Their exospheres are extended over very large distances (> 10 planet radii), where the structure of the escaping planetary wind is affected by essentially 3D factors such as interaction with the stellar wind and the Coriolis force. Therefore the intended 2D modelling approach was upgraded to the global 3D simulations, which along with the aeronomy of the expanding upper atmospheres of exoplanets, included also the modelling of stellar winds. The real stellar radiation spectra (when available) were used in the modelling instead of the initially announced solar analog spectrum. As an additional direction, the methods for analysis of border regions of the transit light curves provided by the Kepler Space Telescope were developed, that enabled the probing of dusty structures possibly present the planetary and stellar material flows in the vicinity of some exoplanets.

• Contribution to the advancement of the field

          The developed in project numerical modelling approaches, analysis methods, and obtained results open a new dimension in the simulation and interpretation of the phenomena of exoplanetary transmission photometry and spectroscopy. 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 integrated in the multi-fluid (M)HD models of the escaping exoplanetary upper atmospheres to enable the calculation of complete photo-chemistry reactions chain. The original 2D models were upgraded to the global 3D numerical code, 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 actual version of the 3D multi-fluid model solves the equations of continuity, momentum, and energy for each atomic, molecular and ionized component. The main processes of particle interconversion are photoionization, electron impact, recombination, and charge exchange. Photoionization also leads to the heating of material by the generated photoelectrons. For each particular star, an appropriate XUV spectrum in the range of 10-912 Å is used. The transmission and attenuation of the XUV flux is calculated in each spectral interval in accordance with the wavelength-dependent absorption cross section. Besides of the radiative heating, the model includes also the cooling effect due to excitation of atomic hydrogen and infrared radiation of the H3+ molecule. The momentum exchange between various components occurs due to ion-atom and Coulomb collisions. The upper atmosphere of modelled giant exoplanets is taken to consist of H, H+, H2, H2+, H3+, He, and He+ components. In addition, the energetic neutral hydrogen atoms (ENAs), generated by charge-exchange between the planetary hydrogen and stellar wind protons, are considered as a separate component. At the same time, the model admits the inclusion of additional species, like, e.g., in the study of absorption by heavy minor species for HD 209458b (OI, CII, SiI, MgI, MgII) and WASP-12b (MgII). Besides of the escaping planetary atmosphere, the model also simulates (based on the same algorithms) the expanding stellar wind, enabling a self-consistent global view of the interacting planetary and stellar material flows (Fig.1). The code is implemented in a non-inertial spherical frame, centred at the planet and rotating in phase with its orbital motion. However, the planet itself can rotate with any period. The non-inertial forces are introduced via the generalized gravitational potential and the Coriolis force. The stellar radiation pressure force is also taken into account. The code’s solver is fully parallelized for performing on HPC. This model appears a cornerstone of the project goals, its major innovation and achievement. For the terrestrial type exoplanets the N2 and CO2 dominated atmospheres were modelled with the improved version of 1D Kompot Code, based on first-principles, taking into account the hydrodynamics and the main chemical and thermal processes in the upper atmosphere of a planet.       

          Along with the elaboration of the global 3D multi-fluid model, a dedicated Python script was developed, based on the library provided by the Visualization Toolkit (VTK, www.vtk.org), that proprietary reads formats of the model. The script enables the creation of a 3D structured-grid-point file that can be imported into the Paraview (https://www.paraview.org - an application based on the VTK library), providing the volume rendering to visualize the 3D data (e.g. Fig.1). The script and its performance can be further customized using a number of (optional) parameters that are explained in detail in a ReadMe file available on Google Drive along with the script (https://drive.google.com/open?id=1CALA7JU4KecPPdMlgVMlLZZ740hEwJIo). The ReadMe file also explains the setup process as well as the visualization pipeline to use in Paraview in order to produce 3D visualizations.

            Within the direction, dedicated to the analysis of the transit light curves, provided by the Kepler Space Telescope, to detect the photometric manifestations of possible optically opaque dusty structures in the streams of escaping planetary wind, a special technique was developed for analyzing the pre- and post-transit parts of the light curves. It is based on the calculation and statistic comparison of the flux gradients before and after the transit for the time intervals, which characterize different regions near the transiting object.

• New scientific/scholarly advances

(1)Revealing of basic trends of the stellar and planetary winds interaction: The interaction of escaping upper atmosphere of a hydrogen rich non-magnetized hot Jupiter with the stellar wind of its host G-type star at different orbital distances was simulated using the self-consistent 2D multi-fluid hydrodynamic model and the realistic Sun-like spectrum of XUV. Two different regimes of the planetary and stellar winds interaction have been modelled. These regimes are: 1) the “captured by the star” regime, when the tidal force and pressure gradient drive the planetary material beyond the Roche lobe forming a two-stream structure of the flow with one stream directed towards the star and another outwards, and 2) the “blown by the wind” regime, when sufficiently strong stellar wind confines the escaping planetary atmosphere and channels it into the tail. It was shown that for the typical for solar-type stars, the escaping planetary wind of a typical hot Jupiter appears in the "captured by a star" regime. However, under an extreme stellar wind conditions with an order of magnitude higher ram pressure, or at sufficiently large orbital distances, leading to decrease of the tidal forces, the planetary wind turns to the "blown by the wind" regime. In this case, a shock wave is formed around the exoplanet within the Roche lobe. The detailed simulation of the structure and composition of multi-component planetary and stellar wind flows in the interaction region for both regimes was done for the first time (Published in Saikhislamov et al. 2016).

(2)Modelling of the ENAs generation around exoplanets and Lyα absorption: For the first time, the cloud of ENAs formed by charge exchange between the planetary H atoms and stellar wind protons was simulated using the self-consistent multi-fluid hydrodynamic description, including all four components involved in the interaction: the planetary hydrogen, its ions, stellar protons, and ENAs. It was shown for the first time that the escaping planetary wind remains essentially collisional and strongly coupled up to distances of tens of planetary radii, due to the charge exchange reaction between the H atoms and ions and Coulomb collisions. The revealed location and shape of the ENA cloud in 3D, either as a paraboloid shell between ionopause and bowshock (for the “blown by the wind” regime), or as a turbulent layer at the contact boundary between the planetary stream and stellar wind (for the “captured by the star” regime) appeared of importance for the modelling and interpretation of Lyα absorption in exoplanetary transits (Published in Saikhislamov et al. 2016, Khodachenko et al. 2017).

(3)Conclusion on the role of stellar radiation pressure in the acceleration of ENAs and HeI: It was shown for the first time, with the numerical modeling and analytical estimates, that Lyα radiation pressure, which was traditionally considered as the main mechanism for the production of ENAs, does not work for the typical hot exoplanets. The escaping planetary wind in fact remains dense even at long distances from the planet, and Lyα radiation does not penetrate deep into it, being absorbed in a thin transition layer. Therefore, the radiation force acts as just a surface pressure, similar to the ram pressure of the stellar wind, which is usually much higher. Besides of that, the planetary wind flow remains strongly coupled, with the momentum exchange between atoms and protons taking place (mainly due to the charge-exchange) at much smaller scales than the characteristic size of the system. This redistributes the radiation pressure force, acting on H atoms, over a much larger number of particles, and reduces its effect. Altogether, the main source of ENAs, and related significant absorption in the blue wing of Lyα, line is the charge-exchange reaction between the planetary H atoms and stellar wind protons (Published in Saikhislamov et al. 2016, 2020b, Khodachenko et al. 2017, 2019, Kislyakova et al. 2019).At the same time the stellar radiation pressure may appear crucial factor in the dynamics of other species in the planetary wind. In particular, it was shown in Khodachenko et al. (2021) that the radiation pressure acting on metastable HeI strongly affects the shape of the absorption profiles of WASP-107b.

(4)Characterization of the dynamic plasmaspheres of exoplanets: For the first time, a self-consistent multi-component, global modelling of the energized by stellar radiation outflowing atmospheres of HD 209458b, WASP-12b, WASP-107b, π Men c, GJ3470b, GJ436b and the surrounding stellar winds was performed in 3D. The absorption in main resonance lines (Lyα, HeI, OI, CII, SiI, MgI, MgII) was simulated and fitted to observations (Hubble and WASP) enabling the probing of atmospheric composition, stellar radiation, and plasma environments (Published in Saikhislamov et al. 2018a,b, 2020a,b,c, Khodachenko et al. 2019, 2021, Dwivedi et al. 2019, Berezutsky et al. 2019).

(5)Basic study of the stellar wind and planetary magnetic field effects: In continuation of the self-consistent 2D MHD modelling of the escaping planetary wind of a magnetized hot Jupiter, which in the case of a perpendicular to the orbital plane magnetic dipole of the planet revealed the formation of an equatorial magnetodisk (Khodachenko et al. ApJ 2015), the structure of the planetary wind flow was for the first time calculated for the case when the immersed in the stellar wind, planetary dipole is pointed towards the star. The current sheet of magnetodisk was also formed in this case, but it had the form of a cylinder surface extended along the planet-star axis. The surface of the current sheet was located near the magnetopause separating the stellar wind and planetary plasmas. Besides of that, using the 3D MHD model, the influence of magnetic field of the stellar wind on its interaction with the exosphere of a non-magnetized hot Jupiter and the generation of ENAs was investigated. A layer of an induced magnetic field of high intensity was found to form in the sub-Alfvénic stellar wind. It resulted in a significant displacement of the magnetosphere boundary towards the planet. Comparison of the model calculations with observations allowed estimating of the magnetic moment of HD 209458b at the level of 10–20% of the Solar System’s Jupiter value (Published in Erkaev et al. 2017). Further, the modelled magnetospheric plasma parameters and field topology were used to study the possibility of observing of the radio emission from hot Jupiters. It was found that the dense and strongly ionized exosphere around the planets significantly restricts the generation and propagation of the cyclotron radiation, as the plasma frequency is usually higher than the electron cyclotron frequency (Published in Weber et al. 2017a,b).

(6)Escape and mass loss of the terrestrial type atmospheres: The transonic hydrodynamic escape of atmosphere was calculated for the first time for an Earth analog planet at 1AU orbit around a young active solar-mass star, using the Kompot Code. The escaping planetary wind dominated by atomic N and O, and their ions was shown to provide mass loss rates, which would erode the modern Earth’s atmosphere in less than 0.1 Myr. Such extreme mass loss suggests that an Earth-like atmosphere cannot form on the planet within the habitable zone (HZ) of an active star. Instead, such an atmosphere can only form after the activity of the star has decreased to a much lower level (Published in Johnstone et al. 2019).Besides of that, the Lyα transit signatures of a hypothetic Earth-sized planet placed in the HZ of the M dwarf GJ 436 were modelled and investigated for the cases of H- and N- dominated atmospheres, as well as for N-dominated atmosphere with an amount of H equal to that of the Earth. The multi-species Direct Simulation Monte Carlo (DSMC) code was used to simulate the planetary exosphere. The modelling revealed that only an Earth-like planet with H-dominated atmosphere can be detected in the HZ of GJ 436 by the present day Space Telescope Imaging Spectrograph on board of Hubble. Neither a pure nitrogen, nor the present Earth analog atmospheres are detectable (Published in Kislyakova et al. 2019). Additionally, the evolution of the polar ion outflow from the open magnetic field line bundle, which is the dominant escape mechanism for the modern Earth, was investigated using the DSMC simulations.The corresponding estimations of the upper limit on the escape rate for the Earth, starting from 3 Gyr ago to present, were made for different mixing ratios of oxygen. According to this study, the main factors that governed the polar outflow in the considered time period are the evolution of the solar XUV radiation and the atmosphere's composition. The evolution of the Earth's magnetic field plays a less important role (Published in Kislyakova et al. 2020).

(7)Detection of dusty phenomena in the vicinity of giant exoplanets: Using linear approximation of pre- and post- transit parts of the light curves of 118 Kepler objects of interest (KOIs) after their preliminary whitening and phase-folding, the corresponding flux gradients G1 and G2, were calculated before and after the transit border for two different time intervals: (a) from 0.03 to 0.16 days and (b) from 0.01 to 0.05 days, which characterize the distant and adjoining regions near the transiting object, respectively. While in the distant region all flux gradients clustered around zero, revealing the absence of obscuring matter there, significantly negative gradients G1 were found in the adjoining region of 17 hot Jupiters, whereas G2 remained ~0. This effect was also reproduced with the models, using a stochastic obscuring precursor ahead the planet. The sporadic nature of the discovered phenomenon explains that it was not found earlier, and only the analysis of phase-folded transit light curves, prepared on the basis of the whole duration of observations, made its detection possible. Such phenomena may be caused by dusty atmospheric outflows, erosion and tidal decay of moonlets, or background circumstellar dust accumulated in electrostatic or magnetic traps in front of the mass-losing exoplanets (Published in Arkhypov et al. 2019). Additionally, the elaborated analysis method and the transit light curve modelling approaches were used to detect possible deviations of the shape of transiting exoplanetary shadows from the circular ones and to search in this way for the photometric manifestations of the non-spherical dusty obscuring structures near the planets (e.g., exorings). The key element of this methodology consists in using the derivatives of the transit light curve during the ingress and egress phases. Of 23 preselected candidate exoplanets, 7 objects were found to have peculiar non-circular shadows. Among them, Kepler-45b and Kepler-840b are the most intriguing, with the strongly elongated shadows (Published in Arkhypov et al. 2021).

(8)Electric current dissipation effects in the partially ionized magnetized plasmas: As applied to hot exoplanets, namely HD 209458b, the presence of the planetary magnetic field and the escaping flow of the partially ionized upper atmospheric material should cause, due to Cowling conductivity, an additional dissipation of the transverse electric currents. At the same time, since the dissipated electric current is generated due to the motion of the escaping planetary wind across the magnetic field, and since the slip between protons and atoms is small, in particular because of the continuously going photo-ionization and charge exchange resulting in the strong coupling of the ionized and neutral components, the energy released due to Cowling dissipation accounts for only a small fraction of the kinetic and thermal energy of the planetary wind. However, this type of dissipation might be important in the localized regions of dynamically changing magnetic fields, e.g., at the points of the magnetodisk reconnection (Published in Ballester et al. 2018).

• Most important hypotheses / research questions developed

(i) Revealing and characterizing of basic regimes of the stellar and planetary winds interaction;

(ii) Conclusion on the role of the stellar radiation pressure in the acceleration of ENAs and HeI;

(iii) Revealing of the 3D shape and location of the ENA cloud and production region;

(iv) Explanation and simulation of the spectral lines’ absorption profiles and related mechanisms.

• Development of new methods

(i) Global 3D multi-fluid self-consistent model of the interacting stellar and planetary winds;

(ii) Simulation tool for the transmission spectroscopy phenomena on the basis of 3D (M)HD modelling;

(iii) Visualization tool for the 3D simulated data.

• Added value of the international collaboration

The implementation of the project was based solely on the cooperation of the Austrian and Russian teams. The Russian team was specializing on the development of (M)HD codes, performing calculations and analysis of the results, whereas the Austrian team provided its expertise in the physics of exoplanetary atmospheres and magnetospheres, atmospheric photo-chemistry, stellar winds, and analysis of observational data, taking the lead in selection of exoplanetary targets for the modelling and publishing of the project results in the high-ranking journals. Scientific formulation of the research tasks, interpretation of the simulation results, and preparation of the materials for publications, as well as their presentation at conferences, were done by both teams jointly. The whole project benefited from the availability of the powerful HPC resources on the side of the Russian partner, e.g., the Siberian Supercomputing Center (SSCC) and the Supercomputer of the Novosibirsk State University. Altogether, the joint project resulted in creation of the most advanced and complete numerical code for the global self-consistent modelling of escaping exoplanetary atmospheres interacting with the stellar winds, and the simulation of related transmission spectroscopy phenomena.

(A) The advanced global multi-fluid model developed in the project opens a way for the simulation of stellar weather processes in variety of stellar-planetary systems and to study the evolution of not only planetary objects, but also the astrosphere phenomena, like, e.g., stellar tori and secondary disks. The transmission spectroscopy simulator, integrated in the model, is of potential use for the search and analysis of possible biomarkers in exoplanetary systems.

(B) The created 3D visualization tool can be used to analyse any 3D data. 

(C) The elaborated methodology for the analysis of ingress and egress parts of the transit light curves enabled revealing and correction of the discrepancies in the definition of parameters of transiting exoplanets in the Kepler database, obtained with traditional methods.

(D) Besides of the research work, the project participants took part in the RTD consortium the European H2020 project Europlanet-2020-RI.

  I.  Papers in peer-reviewed Journals:                    

1. Khodachenko, M. L., Shaikhislamov, I. F., Fossati, L., Lammer, H., Rumenskikh, M.S., Berezutsky, A. G., Miroshnichenko, I. B., Efimof, M.A., Simulation of 10830 Å absorption with a 3D hydrodynamic model reveals the solar He abundance in upper atmosphere of WASP-107b, MNRAS: Letters, 2021, slab015 (DOI: doi.org 10.1093/mnrasl/slab015)
2. Arkhypov, O.V., Khodachenko, M.L., Hanslmeier, A., Revealing of peculiar exoplanetary shadows from transit light-curves, Astron. & Astrophys., 2021, 646, A136 (DOI: doi.org/10.1051/0004-6361/202039050).
3. Owen, J.E., Shaikhislamov, I.F., Lammer, H., Fossati, L., Khodachenko, M.L., Hydrogen Dominated Atmospheres on Terrestrial Mass Planets: Evidence, Origin and Evolution, Space Sci. Rev., 2020, 216, 129 (DOI: https://doi.org/10.1007/s11214-020-00756-w)
4. Shaikhislamov, I. F., Fossati, L., Khodachenko, M. L., Lammer, H., García Muñoz, A., Youngblood, A., Dwivedi, N. K., Rumenskikh, M. S., Three-dimensional hydrodynamic simulations of the upper atmosphere of π Men c: comparison with Lyα transit observations, Astron. & Astrophys., 2020a, 639, A109 (https://doi.org/10.1051/0004-6361/202038363).
5. Shaikhislamov, I.F., Khodachenko, M.L., Lammer, H., Berezutsky, A.G., Miroshnichenko, I.B., Rumenskikh, M.S., Three-dimensional modelling of absorption by various species for hot Jupiter HD 209458b, MNRAS, 2020b, 491, 3435–3447 (DOI: doi.org/10.1093/mnras/stz3211, Open Access)
6. Shaikhislamov, I. F., Khodachenko, M. L., Lammer, H., Berezutsky, A. G., Miroshnichenko, I. B., Rumenskikh, M. S., Global 3D hydrodynamic modeling of absorption in Lyα and He 10830 Å lines at transits of GJ3470b. MNRAS, 2020c, 500(1), 1404-1413 (DOI: 10.1093/mnras/staa2367).
7. Kislyakova, K. G., Johnstone, C. P., Scherf, M., Holmstroem, M., Alexeev, I. I., Lammer, H., Khodachenko, M. L., Guedel, M., Evolution of the Earth’s polar outflow from mid-Archean to present, JGR Space Phys., 2020, 125, e2020JA027837, (DOI: doi.org/10.1029/2020JA027837).
8. Arkhypov, O.V., Khodachenko, M.L., Hanslmeier, A., Dusty phenomena in the vicinity of giant exoplanets, Astron. & Astrophys., 2019, 631, A152 (DOI: doi.org/10.1051/0004-6361/201936521)
9. Khodachenko, M.L., Shaikhislamov, I.F., Lammer, H., Berezutsky, A.G., Miroshnichenko, I.B., Rumenskikh, M.S., Kislyakova, K.G., Dwivedi, N.K., Global 3D hydrodynamic modeling of in-transit Lyα absorption of GJ436b, ApJ, 2019, 885:67 (DOI: doi.org/10.3847/1538-4357/ab46a4, Open Access)
10. Dwivedi, N. K., Khodachenko, M.L., Shaikhislamov, I. F., Fossati, L., Lammer, H. Sasunov, Y.L., Berezutskiy, A. G. Miroshnichenko, I. B., Kislyakova, K. G., Johnstone, C. P., Guedel, M., Modelling atmospheric escape and Mg II near-ultraviolet absorption of the highly irradiated hot Jupiter WASP-12b, MNRAS, 2019, 487, 4208–4220 (DOI: 10.1093/mnras/stz1345).
11. Berezutsky, A. G., Shaikhislamov, I. F., Miroshnichenko, I. B., Rumenskikh, M. S., Khodachenko, M.L., Interaction of the Expanding Atmosphere with the Stellar Wind around Gliese 436b, Solar System Research, 2019, 53, No.2, p.138–145 (in Russian appeared in Astronomicheskii Vestnik, 2019, 53, p.147–154, ISSN 0038-0946) (DOI: 10.1134/S0038094619020011)
12. Johnstone, C. P., Khodachenko, M.L., Lüftinger, T., Kislyakova, K. G., Lammer, H., Güdel, M., Extreme hydrodynamic losses of Earth-like atmospheres in the habitable zones of very active stars, Astron. & Astrophys., 2019, 624, L10 (DOI: doi.org/10.1051/0004-6361/201935279, Open Access).
13. Kislyakova, K. G., Holmström, M., Odert, P., Lammer, H., Erkaev, N. V., Khodachenko, M. L., Shaikhislamov, I. F., Dorfi, E., Güdel, M., Transit Lyman-α signatures of terrestrial planets in the habitable zones of M dwarfs, Astron. & Astrophys., 2019, 623, id.A131 (DOI: 10.1051/0004-6361/201833941).
14. Shaikhislamov, I.F., M.L. Khodachenko, H. Lammer, A. G. Berezutsky, I. B. Miroshnichenko, M. S. Rumenskikh, 3D Aeronomy modelling of close-in exoplanets, MNRAS, 2018a, 481, 5315–5323 (DOI: 10.1093/mnras/sty2652)
15. Shaikhislamov, I. F., Khodachenko, M. L., Lammer, H., Fossati, L., Dwivedi, N., Güdel, M., Kislyakova, K.G., Johnstone, C.P., Berezutsky, A. G., Miroshnichenko, I. B., Posukh, V.G., Erkaev, N.V., Ivanov, V.A., Modeling of absorption by heavy minor species for the hot Jupiter HD 209458b, Astrophysical Journal, 2018b, 866:47 (DOI: doi.org/10.3847/1538-4357/aadf39 Open access).
16. Ballester, J.L., Alexeev, I.I., Collados, M., Downes, T., Pfaff, R.F., Gilbert, H., Khodachenko, M.L., Khomenko, E., Shaikhislamov, I.F., Soler, R., Vázquez-Semadeni, E., Zaqarashvili, T., Partially Ionized Plasmas in Astrophysics, Space Sci. Rev. 2018, 214:58 (DOI: doi.org/10.1007/s11214-018-0485-6)
17. Génot, V., Beigbeder, L., Popescu, D., Dufourg, N., Gangloff, M., Bouchemit, M., Caussarieu, S., Toniutti, J.-P., Durand, J., Modolo, R., André, N., Cecconi, B., Jacquey, C., Pitout, F., Rouillard, A., Pinto, R., Erard, S., Jourdane, N., Leclercq, L., Hess, S., Khodachenko, M.L., Al-Ubaidi, T., Scherf, M., Budnik, E., Science data visualization in planetary and heliospheric contexts with 3DView, Planetary and Space Science, 2018, 150, 111–130 (Open Access:  doi.org/10.1016/j.pss.2017.07.007)
18. Khodachenko, M.L., Shaikhislamov, I.F., Lammer, H., Kislyakova, K.G., Fossati, L., Johnstone, C.P., Arkhypov, O.V., Berezutsky, A.G., Miroshnichenko, I.B., Posukh, V.G., Lyα Absorption at Transits of HD 209458b: A Comparative Study of Various Mechanisms Under Different Conditions, Astrophysical Journal, 2017, 847:126 (DOI: doi.org/10.3847/1538-4357/aa88ad)
19. Weber, C., Lammer, H., Shaikhislamov, I. F., Chadney, J. M., Khodachenko, M. L., Grießmeier, J.-M., Rucker, H. O., Vocks, C., Macher, W., Odert, P., Kislyakova, K. G., How expanded ionospheres of Hot Jupiters can prevent escape of radio emission generated by the cyclotron maser instability, MNRAS, 2017a, 469, p.3505-3517 (DOI: 10.1093/mnras/stx1099).
20. Erkaev N.V., Odert P., Lammer H., Kislyakova K.G., Fossati L., Mezentsev A.V., Johnstone C.P., Kubyshkina D.I., Shaikhislamov I.F., Khodachenko M.L., Effect of stellar wind induced magnetic fields on planetary obstacles of non-magnetized hot Jupiters, MNRAS, 2017, 470(4), 4330-4336 (DOI: 10.1093/mnras/stx1471)
21. Shaikhislamov, I.F., Khodachenko, M.L., Lammer, H., Kislyakova, K.G., Fossati, L., Johnstone, C.P., Prokopov, P.A., Berezutsky, A.G., Zakharov, Yu.P., Posukh, V.G., Two regimes of interaction of a Hot Jupiter’s escaping atmosphere with the stellar wind and generation of energized atomic hydrogen corona, The Astrophysical Journal, 2016, 832, art.id. 173 (DOI: dx.doi.org/10.3847/0004-637X/832/2/173)
22. Erkaev, N.V., Lammer, H., Odert, P., Kislyakova, K.G., Johnstone, C.P., Güdel, M., Khodachenko, M.L., EUV-driven mass-loss of protoplanetary cores with hydrogen-dominated atmospheres: the influences of ionization and orbital distance, Monthly Notices of the Royal Astronomical Society, 2016, 460, 1300-1309 (DOI:10.1093/mnras/stw935)

   II. Papers in Proceedings of Conferences:

1. Kislyakova, K., C. Johnstone, M. Scherf, M. Holmström, I. Alexeev, H. Lammer, M.L.Khodachenko, M. Güdel, Earth’s polar outflow evolution from mid-Archean to present, European Planetary Science Congress 2020, Göttingen, Sep 2020 (DOI: doi.org/10.5194/epsc2020-200).
2. Shaikhislamov, I.F., Khodachenko M.L., Global 3D hydrodynamic modeling of GJ3470b and transit absorption in Lyα and He 10830 Å lines, European Planetary Science Congress 2020, Göttingen, Sep 2020 (DOI: doi.org/10.5194/epsc2020-147).
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