Перегляд за Автор "Nazarenko, S. V."

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  • Ескіз
    Документ
    3D numerical hydrodynamical models of the precessing thick accretion disk and ON- and OFF-state generations in microquasars
    (Одеський національний університет імені І. І. Мечникова, 2017) Nazarenko, V. V.; Nazarenko, S. V.
    The thick accretion disk and donor’s wind on the example of CYG X-1 are computed. The main aim of the present simulations is to calculate the precessing thick accretion disk and ON- and OFF-state generation by the methods of 3D numerical hydrodynamics. The main task of the present research is to investigate the dependencies of the central disk temperature and mass accretion rate versus time. Non-stationary Euler’s hydrodynamical equations are resolved by astrophysical variant of large-particle method by Belotserkovskii & Davydov. The ON- and OFF-state generation for the precessing thick accretion disk was setting. The correlation between radio flux and X-ray was setting. Our present calculations also show that in the cases of the thick accretion disk the jet velocities will be close to 0.24-0.26 of light speed (see for instance SS433) and on contrary in the cases of a thin accretion disk jet velocities will be close to 0.98-0.99 of light speed (see for instance CYG X-1).
  • Ескіз
    Документ
    3D numerical hydrodynamical simulations of a radiation-driven jet launch and disappearing over low/hard state
    (Одеський національний університет імені І. І. Мечникова, 2016) Nazarenko, V. V.; Nazarenko, S. V.
    In the present research we have calculated 3D numerical hydrodynamical simulations of a radiation-driven jet launch and disappearing over low/hard state. The calculations show that the jet launch occurs at the beginning of the low/hard state over 10-30 minutes of the orbital time. The jet disappearing occurs over the short time scale (of the order of 10-30 minutes of the orbital time) at the end of the low/hard state. The calculations also show that the temperature near the accretor is increased in 100-200 times over low/hard state relatively high/soft. The mass accretion rate in the disc is anti-correlated with the temperature near the accretor in our calculations.
  • Ескіз
    Документ
    3D numerical hydrodynamical simulations of a radiation-driven jet launch and disappearing over low/hard state
    (Одеський національний університет імені І. І. Мечникова, 2016) Nazarenko, V. V.; Nazarenko, S. V.
    In the present research we have calculated 3D numerical hydrodynamical simulations of a radiation-driven jet launch and disappearing over low/hard state. The calculations show that the jet launch occurs at the beginning of the low/hard state over 10-30 minutes of the orbital time. The jet disappearing occurs over the short time scale (of the order of 10-30 minutes of the orbital time) at the end of the low/hard state. The calculations also show that the temperature near the accretor is increased in 100-200 times over low/hard state relatively high/soft. The mass accretion rate in the disc is anti-correlated with the temperature near the accretor in our calculations.
  • Ескіз
    Документ
    THE NUMERICAL THREE-DIMENSIONAL HYDRODYNAMIC SIMULATION OF COLLIDING STELLAR WINDS IN A CLOSE BINARY SYSTEM
    (Astroprint, 2013) Nazarenko, V. V.; Glazunova, L. V.; Nazarenko, S. V.
    In the present numerical study the stellar winds from both supergiant-components of a detached close binary system (CBS) are simulated applying methods of the three-dimensional numerical hydrodynamics. The simulated winds collide in the space between the components, forming a stationary shock wave. That shock wave has geometrically intricate shape that consists of several separate filamentary structures. The temperature in the shock wave is about 105K, and the temperature in the space adjacent to the shock wave is around 104 - 1.5 104K. Away from the line-of-centres the shock wave is curved due to the effect of the Coriolis forces and greatly expands under the gas pressure at that. At a distance of about two orbital separations from the line-of-centres the shock wave expands so much that it is practically smearing out in space.
  • Ескіз
    Документ
    THE NUMERICAL THREE-DIMENSIONAL HYDRODYNAMIC SIMULATION OF THE -RAY BURSTERS AND X-RAY BURSTERS
    (Astroprint, 2013) Nazarenko, V. V.; Glazunova, L. V.; Nazarenko, S. V.
    An radiative wind accretion onto the compact object in a detached close binary system (CBS) where one of the components is a supergiant with radiation stellar wind that blows from its surface, and another component is a compact object (black hole or neutron star), is simulated applying methods of three-dimensional numerical hydrodynamics. The simulation of bursts similar to the gamma-ray bursters and X-ray bursters, i.e. isolated bursts with nearly zero in time ascending and descending branches with amplitudes from 6 - 7m to 15 - 18m, commences in the vicinity of the compact object when the precession of the donor star starts. Due to the course numerical spatial grid of 0.01 units of the orbital separation, the duration of such isolated bursts is 10-40 minutes of the orbital time. The burst simulation is as follows: when the donor stars precession starts, small grid-cell-sized regions of higher density appear in the vicinity of the compact object due to the RayleighTaylor instability. The temperature in one of those regions increases abruptly when they interact with the stellar wind from the donor star. Prior to the temperature increase, the indicated regions were radiopaque. When the temperature reaches its peak, those regions become radiolucent, and all energy contained there is momentarily illuminated, giving off a burst that appears as an isolated sharp peak. That is how the bursts similar to the gamma-ray bursts and X-ray bursts are simulated.
  • Ескіз
    Документ
    THREE-DIMENSIONAL NUMERICAL HYDRODYNAMIC SIMULATION OF ON- AND OFF-STATES IN MICROQUASARS AND QUASARS
    (Astroprint, 2014) Nazarenko, V. V.; Nazarenko, S. V.
    As is shown in the present computations performed using three-dimensional numerical astrophysical methods, in microquasars in the course of precession of the accretion disc blown by the donor’s wind the on- and off-states start being generated in the disc. In our case, the transition between these states takes 30-40 minutes of the orbital time. In the off-state the temperature changes discretely, i.e. such a change appears as separate sharp peaks, which almost merge with each other over time.
  • Ескіз
    Документ
    Three-dimensional numerical hydrodynamical simulation of low/hard and high/soft states in accretion discs of microquasars and quasars on base of undefined precession
    (Одеський національний університет імені І. І. Мечникова, 2015) Nazarenko, V. V.; Nazarenko, S. V.
    In this study, the models of slaved precession of accretion disc and donors radiationdriven wind were performed using three-dimensional numerical astrophysical methods by the example of microquasar Cyg X-1. As is shown, in the course of precession of the accretion disc blown by the donor’s wind the states with high and low temperature (low and high mass accretion rate, respectively) start being generated in the centre of disc. Our computations of disc precession performed on base of undefined precession that means each point of rotation axis of accretion disc makes unclosed difficult curve instead of a circle as it is in case of definite precession. In this case, the transition between states of high and low temperature takes place irregularly and not depend on precession period. The duration of transition between these both states is less than intervals of states on several orders of magnitudes.