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Найдено документов в текущей БД: 5

    Plasma and magnetic field parameters in the vicinity of short-periodic giant exoplanets
[Text] / N. V. Erkaev [et al.] // Astrophys. J. Suppl. Ser. - 2005. - Vol. 157, Is. 2. - P396-401, DOI 10.1086/427904. - Cited References: 48 . - ISSN 0067-0049
РУБ Astronomy & Astrophysics

Аннотация: During the past years, more than 130 giant planets were discovered in extrasolar planetary systems. Because of the fact that the orbital distances are very close to their host stars, these planets are embedded in a dense stellar wind, which can pick up planetary ions. We model the stellar wind interaction of the short-periodic exoplanets OGLE-TR-56b and HD 209458b at their orbital distances of approximate to 0.023 AU and approximate to 0.045 AU, by calculating the Alfven Mach number and the magnetosonic Mach number in the stellar wind plasma flow. We then analyze the different plasma interaction regimes around the planetary obstacles, which appear for different stellar wind parameters. Our study shows that the stellar wind plasma parameters like temperature, interplanetary magnetic field, particle density, and velocity near planetary obstacles at orbital distances closer than 0.1-0.2 AU have conditions such that no bow shocks evolve. Our study shows also that these close-in exoplanets are in a submagnetosonic regime comparable to the magnetospheric plasma interaction of the inner satellites of Jupiter and Saturn. Furthermore, we compare the results achieved for both exoplanets with the Jupiter-class exoplanet HD 28185b at its orbital distance of approximate to 1.03 AU. Finally, we also discuss the behavior of the stellar wind plasma flow close to the planetary obstacles of two highly eccentric gas giants, namely, HD 108147b and HD 162020b. Because of their eccentric orbits, these two exoplanets periodically experience both regimes with and without a bow shock. Finally, we simulate the neutral gas density of HD 209458b with a Monte Carlo model. By using the plasma parameters obtained in our study we calculate the ion production and loss rate of H+ with a test particle model. Our simulations yield H+ loss rates for HD 209458b or similar giant exoplanets in orders of about 10(8)-10(9) g s(-1). These ion loss rates are at least 1 order of magnitude lower than the observed loss rate of evaporating neutral H atoms. Our study indicates, that similar gas giants at larger orbital distances have lower ion loss rates. Thus, the dominating component of particle loss of short-periodic Jupiter-class exoplanets will be neutral hydrogen.


Доп.точки доступа:
Erkaev, N.V.; Еркаев, Николай Васильевич; Penz, T.; Lammer, H.; Lichtenegger, H.I.M.; Biernat, H.K.; Wurz, P.; Griessmeier, J.M.; Weiss, W.W.

    How to distinguish between kink and sausage modes in flapping oscillations?
[Text] / D. I. Kubyshkina [et al.] // J. Geophys. Res-Space Phys. - 2014. - Vol. 119, Is. 4. - P. 3002-3015, DOI 10.1002/2013JA019477. - Cited References: 32. - We thank C. W. Carlson and J. P. McFadden for use of THEMIS ESA data; K. H. Glassmeier, U. Auster, and W. Baumjohann for the use of FGM data provided under the lead of the Technical University of Braunschweig and with financial support through the German Ministry for Economy and Technology and the German Center for Aviation and Space (DLR) under contract 50 OC 0302. The work was partly supported by SPbU grant 11.38.84.12, by RFBR grants 12-05-00152-a and 12-05-00918-a, and by the grant for support of leading Scientific schools 2836.2014.5. The work of S. Dubyagin and N. Ganushkina was partly supported by the Academy of Finland. This work was supported by the Austrian Science Fund (FWF): I193-N16. N. V. E acknowledges the support by the International Space Science Institute (ISSI, Switzerland) and discussions within the ISSI Team 214 on Flow-Driven Instabilities of the Sun-Earth System. The research has received funding also from the European Union Seventh Framework Programme [FP7/2007-2013] under grant agreement 269198-Geoplasmas (Marie Curie International Research Staff Exchange Scheme) and 218816 (SOTERIA project). . - ISSN 2169-9380. - ISSN 2169-9402
РУБ Astronomy & Astrophysics

Аннотация: Flapping waves are most noticeable large-scale perturbations of the magnetotail current sheet, whose nature is still under discussion. They represent rather slow (an order of magnitude less than typical Alfven speed) waves propagating from the center of the sheet to its flanks with a typical speed of 20-60 km/s, amplitude of 1-2 R-e and quasiperiod of 2-10 min. The double-gradient MHD model, which was elaborated in Erkaev et al. (2007) predicts two (kink and sausage) modes of the flapping waves with differences in their geometry and propagation velocity, but the mode structure is hard to resolve observationally. We investigate the possibility of mode identification by observing the rotation of magnetic field and plasma velocity vectors from a single spacecraft. We test theoretical results by analyzing the flapping oscillations observed by Time History of Events and Macroscale Interactions during Substorms spacecraft and confirm that character of observed rotation is consistent with kink mode determination made by using multispacecraft methods. Also, we checked how the existence of some obstructive conditions, such as noise, combined modes, and multiple sources of the flapping oscillations, can affect on the possibility of the modes separation with suggested method.

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ИВМ СО РАН

Доп.точки доступа:
Kubyshkina, D.I.; Sormakov, D.A.; Sergeev, V.A.; Semenov, V.S.; Erkaev, N.V.; Еркаев, Николай Васильевич; Kubyshkin, I.V.; Ganushkina, N.Y.; Dubyagin, S.V.; German Ministry for Economy and Technology; German Center for Aviation and Space (DLR) [50 OC 0302]; SPbU [11.38.84.12]; RFBR [12-05-00152-a, 12-05-00918-a]; grant for support of leading Scientific schools [2836.2014.5]; Academy of Finland; Austrian Science Fund (FWF) [I193-N16]; International Space Science Institute (ISSI, Switzerland); European Union [269198, 218816]

    Marangoni convection in a cylinder of finite size
[Text] / E. P. Magdenko // J. Appl. Mech. Tech. Phys. - 2016. - Vol. 57, Is. 1. - P13-19, DOI 10.1134/S002189441601003X. - Cited References:8. - This work was supported by Integration Project of the Siberian Branch of the Russian Academy of Sciences No. 38 and the Russian Foundation for Basic Research (Grant No. 14-01-00067). . - ISSN 0021-8944. - ISSN 1573-8620
РУБ Mechanics + Physics, Applied

Аннотация: This paper considers a liquid in a finite-size cylinder in which Marangoni instability occurs. The upper boundary of the liquid is free and deformable. The problem of the occurrence of convection in a cylindrical container is solved using the method of separation of variables. A homogeneous differential equation of the sixth order with constant coefficients and complex boundary conditions is obtained. An analytical expression for critical Marangoni numbers is derived for the case of monotonic perturbations. The case is considered where the liquid in the cylinder is weightless.

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Держатели документа:
Russian Acad Sci, Inst Computat Modeling, Siberian Branch, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Magdenko, E. P.; Integration Project of the Siberian Branch of the Russian Academy of Sciences [38]; Russian Foundation for Basic Research [14-01-00067]

    Onset of Convection in a Cylindrical Container with a Free Boundary
/ V. K. Andreev, E. P. Magdenko // Fluid Dyn. - 2018. - Vol. 53, Is. 2. - P277-284, DOI 10.1134/S0015462818020039. - Cited References:9 . - ISSN 0015-4628. - ISSN 1573-8507
РУБ Mechanics + Physics, Fluids & Plasmas

Аннотация: The problem of small perturbations of the equilibriumstate of a viscous, heat-conducting fluid in a cylindrical container with a deformable free upper boundary, on which heat exchange with the ambient medium is preassigned, is studied. The mathematical modeling of convection is based on Oberbeck-Boussinesq equations. The spectral problem thus obtained is solved using the tau method. As a result, the dependence of the imaginary part of the complex decrement on the Marangoni number is obtained. In the case of monotonic perturbations the neutral curves are plotted as functions of a geometrical parameter, namely, the cylinder height-to-radius ratio. The dependence of the Marangoni number on the physical parameters of the fluid is also obtained.

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Держатели документа:
Siberian Fed Univ, Inst Math & Fundamental Informat, Svobodny Pr 79, Krasnoyarsk 660091, Russia.
Russian Acad Sci, Siberian Branch, Inst Computat Modeling, Krasnoyarsk 660036, Russia.

Доп.точки доступа:
Andreev, V. K.; Magdenko, E. P.

    Thermocapillary Convection with Phase Transition in the 3D Channel in a Weak Gravity Field
/ V. B. Bekezhanova, O. N. Goncharova // Microgravity Sci. Technol. - 2019. - Vol. 31, Is. 4. - P357-376, DOI 10.1007/s12217-019-9691-4. - Cited References:38. - This work was partially supported by the Russian Foundation for Basic Research and the government of Krasnoyarsk region (project No. 18-41-242005). . - ISSN 0938-0108. - ISSN 1875-0494
РУБ Engineering, Aerospace + Thermodynamics + Mechanics

Аннотация: The regimes of joint flows of the evaporating liquid and vapor-gas mixture in a 3D rectangular channel are studied with the help of a partially invariant solution for the convection equations. The effects of thermodiffusion and diffusive thermal conductivity in the gas-vapor phase are additionally taken into account in the governing equations and under interface conditions. A numerical simulation of the 3D fluid flows is carried out for the liquid-gas system like ethanol-nitrogen and HFE-7100-nitrogen under microgravity conditions. The influence of the thermal load, liquid layer thickness and heat-transfer liquid type on the structure of the fluid flows and evaporation characteristics is investigated. The solution allows one to describe the formation of longitudinal thermocapillary rolls observed in the experiments. The evaporative mass flow rate depends essentially on the thermophysical properties of the working liquid. Spatial size and a shape of thermal patterns are determined by the applied thermal load and they can be varied with the change in the liquid layer thickness. Topological structure of the flows (double or quadruple vortex composition) is defined by the combined influence of the thermocapillary and convective mechanisms and phase transition effects. The results discussed in the paper provide motivation for the development of a classification of the 3D flow regimes similar to the Napolitano's classification for 2D flows.

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Держатели документа:
RAS, Inst Computat Modelling SB, Dept Differential Equat Mech, Akademgorodok 50-44, Krasnoyarsk 660036, Russia.
Altai State Univ, Pr Lenina 61, Barnaul 656049, Russia.

Доп.точки доступа:
Bekezhanova, V. B.; Goncharova, O. N.; Russian Foundation for Basic Research; government of Krasnoyarsk region [18-41-242005]