Труды сотрудников ИВМ СО РАН

[Text] / H. Lammer [et al.] // Celest. Mech. Dyn. Astron. - 2005. - Vol. 92, Is. 01.03.2013. - P273-285, DOI 10.1007/s10569-005-0004-4. - Cited References: 27 . - ISSN 0923-2958РУБ Astronomy & Astrophysics + Mathematics, Interdisciplinary Applications

Аннотация: The region around a star where a life-supporting biosphere can evolve is the so-called Habitable Zone (HZ). The current definition of the HZ is based only on the mass-luminosity relation of the star and climatological and meteorological considerations of Earth-like planets, but neglects atmospheric loss processes due to the interaction with the stellar radiation and particle environment. From the knowledge of the planets in the Solar System, we know that planets can only evolve into a habitable world if they have a stable orbit around its host star and if they keep the atmosphere and water inventory during: (i) the period of heavy bombardment by asteroids and comets and (ii) during the host stars' active X-ray and extreme ultraviolet (XUV) and stellar wind periods. Impacts play a minor role for planets with the size and mass like Earth, while high XUV fluxes and strong stellar winds during the active periods of the young host star can destroy the atmospheres and water inventories. We show that XUV produced temperatures in the upper atmospheres of Earth-like planets can lead to hydrodynamic "blow off", resulting in the total loss of the planets water inventory and atmosphere, even if their orbits lie inside the HZ. Further, our study indicates that Earth-like planets inside the HZ of low mass stars may not develop an atmosphere, because at orbital distances closer than 0.3 AU, their atmospheres are highly affected by strong stellar winds and coronal mass ejections (CME's). Our study suggests that planetary magnetospheres will not protect the atmosphere of such planets, because the strong stellar wind of the young star can compress the magnetopause to the atmospheric obstacle. Moreover, planets inside close-in HZ's are tidally locked, therefore, their magnetic moments are weaker than those of an Earth-like planet at 1 AU. Our results indicate that Earth-like planets in orbits of low mass stars may not develop stable biospheres. From this point of view, a HZ, where higher life forms like on Earth may evolve is possibly restricted to higher mass K stars and G stars.


Доп.точки доступа:
Lammer, H.; Kulikov, Y.N.; Penz, T.; Leitner, M.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / T. Penz [et al.] ; ed.: O. Witasse // PLANETARY ATMOSPHERES, IONOSPHERES, AND MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE LTD, 2005. - Vol. 36: 35th COSPAR Scientific Assembly (JUL 18-25, 2004, Paris, FRANCE), Is. 11. - P2049-2056, DOI 10.1016/j.asr.2004.11.039. - Cited References: 20 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: It is known from Pioneer Venus measurements that at the Venusian ionopause wave-like structures develop, which can detach in the form of ionospheric plasma clouds. This phenomenon is assumed to occur due to the Kelvin-Helmholtz instability, which can appear in large regions of the Venusian ionopause. Recent studies of Mars Global Surveyor measurements indicate that wave-like structures and plasma clouds also detach from the Martian ionopause. Therefore, these features seem to be common for the solar wind interaction of non-magnetized planets. We study the conditions at the Martian ionopause with respect to the occurrence of several MHD instabilities. The conditions in the magnetosheath are modeled by a semi-analytical MHD simulation that includes mass loading. The ionospheric parameter needed for the model calculations are taken from a global hybrid model. The stability of the Martian ionopause against the Kelvin-Helmholtz, the Rayleigh-Taylor, and the interchange instability is analyzed. Further, we suggest that including the Hall term in the description of the Kelvin-Helmholtz instability gives a current in the planetary boundary layer resulting in a shear flow compared with the ionospheric plasma, which can lead to an unstable boundary layer near the subsolar point. Since the interchange instability depends on the curvature of the magnetic field lines, we additionally study the influence of the strong curvature of the Martian ionopause due to the localized, remnant, crustal magnetism appearing mainly in the southern hemisphere of Mars. (c) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Penz, T.; Arshukova, I.L.; Terada, N.; Shinagawa, H.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Lammer, H.; Witasse, O. \ed.\

[Text] / M. Blanc, R. Kallenbach, N. V. Erkaev // Space Sci. Rev. - 2005. - Vol. 116: Workshop on Comparative Study of the Outer Planets before the Exploration of Saturn (JAN 12-14, 2004, Bern, SWITZERLAND), Is. 01.02.2013. - P227-298, DOI 10.1007/s11214-005-1958-y. - Cited References: 202 . - ISSN 0038-6308РУБ Astronomy & Astrophysics

Аннотация: This article proposes a short review of our present knowledge of solar system magnetospheres, with the purpose of placing the study of Saturn's inagnetosphere in the context of a comparative approach. We describe the diversity of solar system magnetospheres and the underlying causes of this diversity: nature and magnetization state of the planetary obstacle, presence or not of a dense atmosphere, rotation state of the planet, existence of a system of satellites, rings and neutral gas populations in orbit around the planet. We follow the "russian doll" hierarchy of solar system magnetospheres to briefly describe the different objects of this family: the heliosphere, which is the Sun's magnetosphere; the "elementary" magnetospheres of the inner planets, Earth and Mercury; the "complex" magnetospheres of the giant planets, dominated by planetary rotation and the presence of interacting objects within their magnetospheric cavities, some of which, like Ganymede, to or Titan, produce small intrinsic or induced magnetospheres inside the large one. We finally describe the main original features of Saturn's magnetosphere as we see them after the Voyager fly-bys and before the arrival of Cassini at Saturn, and list some of the key questions which Cassini will have to address during its four-year orbital tour.


Доп.точки доступа:
Blanc, M.; Kallenbach, R.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / S. Muhlbachler [et al.] ; ed.: X. BlancoCano // COMPARATIVE MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2004. - Vol. 33: 2nd World Space Congress/34th COSPAR Scientific Assembly (OCT 10-19, 2002, HOUSTON, TX), Is. 11. - P2103-2107, DOI 10.1016/j.asr.2003.04.052. - Cited References: 10 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: During periods of a persistent southward interplanetary magnetic field, reconnection is initiated at the dayside magnetopause and flux is transported away to the nightside magnetosphere. This is the so-called phenomenon of magnetosphere erosion. In this paper, erosion at the terrestrial magnetopause is studied. A new theoretical approach to study erosion at the magnetopause on the basis of time-dependent reconnection is presented. We calculate the earthward motion of the magnetopause resulting from each reconnection pulse, together with the associated bow shock motion. Thus, the displacement of both boundary layers is presented. (C) 2004 COSPAR. Published by Elsevier Ltd. All rights reserved.


Доп.точки доступа:
Muhlbachler, S.; Semenov, V.S.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kubyshkin, I.V.; Farrugia, C.J.; Langmayr, D.; Vogl, D.F.; BlancoCano, X. \ed.\

[Text] / H. K. Biernat [et al.] // COMPARATIVE RECONNECTION STUDIES AT THE SUN AND IN PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2002. - Vol. 29: D0 1-E3 1 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assmbly (JUL, 2000, WARSAW, POLAND), Is. 7. - P1069-1074, DOI 10.1016/S0273-1177(02)00023-6. - Cited References: 12 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Many observations show a difference between the pressure parallel and perpendicular to the magnetic field. Thus it is reasonable to study the Petschek reconnection mechanism for the set of equations allowing for pressure anisotropy. We study the simplest case of so-called Petschek shocks, where the Alfven discontinuity and the slow shock degenerate to one discontinuity. More specifically, we consider switch-off shocks, where the magnetic field on the downstream side vanishes in lowest order, so that the plasma is isotropic on that side. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Biernat, H.K.; Muhlbachler, S.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Vogl, D.F.; Ivanova, V.V.

[Text] / S. Muhlbachler [et al.] // COMPARATIVE RECONNECTION STUDIES AT THE SUN AND IN PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2002. - Vol. 29: D0 1-E3 1 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assmbly (JUL, 2000, WARSAW, POLAND), Is. 7. - P1113-1118, DOI 10.1016/S0273-1177(02)00033-9. - Cited References: 14 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Magnetic reconnection is a process which allows topological different magnetic fields to interconnect. Thus, in magnetospheric context, reconnection is strongly associated with substorm phenomena. Because many observations show a difference between the pressure parallel and perpendicular to the magnetic field, it is reasonable to study the reconnection mechanism for the set of equations, involving a pressure tensor. Existing theoretical work for isotropic weak reconnection is extended for anisotropic theory. In particular, the reconnection associated discontinuities as the Alfven discontinuity, the slow shock, and the contact discontinuity are generalized for anisotropic pressure. (C) 2002 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Muhlbachler, S.; Biernat, H.K.; Semenov, V.S.; Farrugia, C.J.; Vogl, D.F.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / H. K. Biernat, N. V. Erkaev, C. J. Farrugia // PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE BV, 2001. - Vol. 28: D3 1/C3 3 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assembly (JUL, 2000, WARSAW, POLAND), Is. 6. - P833-839, DOI 10.1016/S0273-1177(01)00525-7. - Cited References: 12 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We use the "magnetic string" approach to integrate the dissipationless MHD equations for a 3-D flow around planetary obstacles, and apply it to some aspects of the flow in the magnetosheath of Venus. Our method has both analytical and numerical components, and is particularly suited to study the structure of the magnetic barrier (depletion layer). Including pick-up processes, we study the contribution to the structure of the Venus magnetosheath made by the pick-up ions. As one main conclusion, we show that the used method leads to a stand-off bow shock position which in good agreement with observations. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Farrugia, C.J.

[Text] / D. F. Vogl [et al.] // PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE BV, 2001. - Vol. 28: D3 1/C3 3 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assembly (JUL, 2000, WARSAW, POLAND), Is. 6. - P851-856, DOI 10.1016/S0273-1177(01)00503-8. - Cited References: 12 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: In this paper we report on the variations of the magnetic field strength and the plasma parameters across a fast shock as functions of upstream Alfven Mach numbers and pressure anisotropy downstream of the shock. In our study we consider an oblique shock where the angle between the magnetic field vector and the normal vector upstream of the shock is chosen to be 45degrees. We further use two threshold conditions of plasma instabilities as additional equations to bound the range of the pressure anisotropy, p(perpendicular to)/p(\\), i.e., the criterion of the mirror instability and that of the fire-hose instability. We found that the variations of the parallel pressure, the parallel temperature, as well as the tangential component of the velocity are most sensitive to the pressure anisotropy downstream of the shock, whereas the variations of the plasma density, the normal velocity, the magnetic field strength, and perpendicular pressure and temperature with respect to the magnetic field show much less pronounced dependence on the anisotropy. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Vogl, D.F.; Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Muhlbachler, S.; Farrugia, C.J.

[Text] / N. V. Erkaev [et al.] // PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE BV, 2001. - Vol. 28: D3 1/C3 3 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assembly (JUL, 2000, WARSAW, POLAND), Is. 6. - P873-877, DOI 10.1016/S0273-1177(01)00522-1. - Cited References: 16 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We study the solar wind flow in the Earth's magnetosheath using a three-dimensional, ideal magnetohydrodynamic (MHD) model with anisotropic plasma pressure. Four different closure relations are examined and compared with each other, i) The double adiabatic model; ii) the empirical relation with respect to the criterion of the anisotropic ion cyclotron instability; iii) the mirror instability criterion, and (iv) the combination of the mirror and the anisotropic ion cyclotron instability. Profiles of magnetic field strength and plasma parameters for the different closure relations are presented and compared with each other along the stagnation stream line between the shock and the obstacle. We find that the main body of the magnetosheath is mirror unstable. This is a reason to combine both, mirror and ion cyclotron instability criteria to close the ideal MHD model. (C) 2001 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Biernat, H.K.; Vogl, D.F.; Farrugia, C.J.

[Text] / H. K. Biernat, N. V. Erkaev, C. J. Farrugia // PLANETARY IONOSPHERES AND MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : ELSEVIER SCIENCE BV, 2000. - Vol. 26: C3 2/D0 9 Symposium of COSPAR Scientific Commission C/B0 5 Symposium of COSPAR Svcientific Commission B held during the 32nd COSPAR Scintific Assembly (JUL, 1998, NAGOYA, JAPAN), Is. 10. - P1587-1591, DOI 10.1016/S0273-1177(00)00085-5. - Cited References: 11 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We study features of flow around Venus using a numerical algorithm to integrate the dissipationless magnetohydrodynamic (MHD) equations, which includes from the start magnetic forces on the flow. We show first that, contrary to previous estimates based on gas dynamics, for a reasonable Alfven Mach number the MI-ID-modelled subsolar magnetosheath is nearly as thick as that obtained from observations. Concentrating next on the region off the subsolar line we present model results for the variation of all plasma and field parameters along paths normal to the ionopause for different values of the solar zenith angle. (C) 2000 COSPAR. Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич; Farrugia, C.J.

[Text] / C. J. Farrugia, H. K. Biernat, N. V. Erkaev // Planet Space Sci. - 1998. - Vol. 46, Is. 5. - P507-514, DOI 10.1016/S0032-0633(97)00225-0. - Cited References: 20 . - ISSN 0032-0633РУБ Astronomy & Astrophysics

Аннотация: The solar wind flow past nonaxisymmetric magnetospheres exhibits features which are absent in the case of axisymmetric magnetospheres such as that of Earth. We discuss results obtained by a numerical integration of the dissipationless MHD equations, under simplifying assumptions, and apply them to the two outer planets Jupiter and Saturn, both of whose magnetospheres depart substantially from axisymmetry. We model these magnetospheres as paraboloids with two different radii of curvature at the subsolar point, L-0 and L-1, where L-0 and L-1 refer to a magnetopause cut containing the rotational axis, and to the rotational equator, respectively (L-0 L-1). The degree of flattening is expressed by a parameter q :


Доп.точки доступа:
Farrugia, C.J.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / C. J. Farrugia, H. K. Biernat, N. V. Erkaev // PLANETARY IONOSPHERES AND MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH-SERIES : PERGAMON PRESS LTD, 1997. - Vol. 20: C3.2 Symposium of COSPAR Scientific Commission C on Planetary Ionospheres and Magnetospheres, at the 31st COSPAR Scientific Assembly (JUL 14-21, 1996, BIRMINGHAM, ENGLAND), Is. 2. - P209-213, DOI 10.1016/S0273-1177(97)00535-8. - Cited References: 15 . - ISBN 0273-1177. - ISBN 0-08-043297-2РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: We discuss results on the solar wind flow past the non-axisymmetric magnetospheres of planets Jupiter and Saturn obtained by integrating numerically the dissipationless MHD equations under simplifying assumptions. We model these equatorially broadened magnetospheres as paraboloids with two different radii of curvature at the subsolar point. The thickness of the magnetosheath and the width and structure of the plasma depletion layer are found to be strong functions of the orientation of the interplanetary magnetic field (IMF). The effect of the IMF on the magnetosheath is strongest (weakest) when the IMF is directed perpendicular (parallel) to the rotational equator. For any intermediate IMF orientation, a smooth rotation of the magnetosheath magnetic field towards the direction of the planet's rotational axis is superimposed on the field strength enhancement (and the density reduction) as the respective magnetopauses are approached. These effects are more pronounced at Jupiter than at Saturn. (C) 1997 COSPAR. Published by Elsevier Science Ltd.


Доп.точки доступа:
Farrugia, C.J.; Biernat, H.K.; Erkaev, N.V.; Еркаев, Николай Васильевич

[Text] / N. V. Erkaev, V. S. Semenov, H. K. Biernat // COMPARATIVE RECONNECTION STUDIES AT THE SUN AND IN PLANETARY MAGNETOSPHERES. Ser. ADVANCES IN SPACE RESEARCH : PERGAMON-ELSEVIER SCIENCE LTD, 2002. - Vol. 29: D0 1-E3 1 Symposium of COSPAR Scientific Commission D held at the 33rd COSPAR Scientific Assmbly (JUL, 2000, WARSAW, POLAND), Is. 7. - P1075-1080, DOI 10.1016/S0273-1177(02)00024-8. - Cited References: 15 . - ISBN 0273-1177РУБ Engineering, Aerospace + Astronomy & Astrophysics + Geosciences, Multidisciplinary + Meteorology & Atmospheric Sciences

Аннотация: Using a two-dimensional, incompressible magnetohydrodynamic (MHD) model, we study unsteady reconnection of antiparallel magnetic fields in the symmetric case. The magnetic reconnection process is initiated by variation of a local resistivity assumed to be a given function of time and spatial coordinates. The diffusion region of reconnection is treated as a thin boundary layer where the perpendicular components of magnetic field and velocity are much smaller than the components of these quantities along the layer. The unsteady MHD equations are solved by a two-step finite difference numerical scheme with an implicit approximation of the magnetic diffusion terms in a uniform right angle grid. In the numerical study, we use the initial conditions related to a uniform current layer without any motion of the plasma. The time-dependent reconnection process is characterized by the following important parameters: A timescale of the local resistivity, a length scale of the local resistivity, a local Reynolds number determined for the maximum resistivity and the length scale of the diffusion region. The numerical results show that the Petschek type reconnection is realized for the sufficiently small length scale and large time scale of the local resistivity, and a moderate local Reynolds number. Using unsteady numerical MHD solution obtained for the diffusion region, we determine the reconnection rate as a function of time by matching of the outer Petschek solution and the internal diffusion region solution. (C) 2002 COSPAR, Published by Elsevier Science Ltd. All rights reserved.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Semenov, V.S.; Biernat, H.K.

[Text] / U. V. Mostl [et al.] // Icarus. - 2011. - Vol. 216, Is. 2. - P476-484, DOI 10.1016/j.icarus.2011.09.012. - Cited References: 27. - This work is supported by the Austrian Science Fund Project P21051-N16 and also by RFBR Grant No. 09-05-91000-ANF_a. H.L. and H.G. are supported by the Helmholtz Association through the research alliance "Planetary Evolution and Life" and by the Austrian Science Fund Project I199-N16. M.Z. and D.K. are supported by the Austrian Science Fund Project I193-N16. . - ISSN 0019-1035РУБ Astronomy & Astrophysics

Аннотация: The Kelvin-Helmholtz instability gained scientific attention after observations at Venus by the spacecraft Pioneer Venus Orbiter gave rise to speculations that the instability contributes to the loss of planetary ions through the formation of plasma clouds. Since then, a handful of studies were devoted to the Kelvin-Helmholtz instability at the ionopause and its implications for Venus. The aim of this study is to investigate the stability of the two instability-relevant boundary layers around Venus: the induced magnetopause and the ionopause. We solve the 2D magnetohydrodynamic equations with the total variation diminishing Lax-Friedrichs algorithm and perform simulation runs with different initial conditions representing the situation at the boundary layers around Venus. Our results show that the Kelvin-Helmholtz instability does not seem to be able to reach its nonlinear vortex phase at the ionopause due to the very effective stabilizing effect of a large density jump across this boundary layer. This seems also to be true for the induced magnetopause for low solar activity. During high solar activity, however, there could occur conditions at the induced magnetopause which are in favour of the nonlinear evolution of the instability. For this situation, we estimated roughly a growth rate for planetary oxygen ions of about 7.6 x 10(25) s(-1), which should be regarded as an upper limit for loss due to the Kelvin-Helmholtz instability. (C) 2011 Elsevier Inc. All rights reserved.


Доп.точки доступа:
Mostl, U.V.; Erkaev, N.V.; Еркаев, Николай Васильевич; Zellinger, M.; Lammer, H.; Groller, H.; Biernat, H.K.; Korovinskiy, D.