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ABSTRACT: In the paper we present results of numerical simulations of magnetorotational model of explosion of magnetized cloud. For
the simulation we used a specially developed 2D implicit numerical scheme on Lagrangian triangular grid with grid reconstruction.
Our results show that due to the amplification of toroidal magnetic field component and transfer of angular momentum, a compression
wave in the envelope of the cloud appears and moves through rapidly decreasing density background. This wave turns into a
shock wave and pushes out part of the envelope of the star. Quantitative estimates of mass and energy carried away are given.
06/2007: pages 145-148;
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ABSTRACT: We present the results of the 2D simulation of a magnetorotational (MR) core-collapse model accompanied by jet formation in the core-collapse model explosion. The initial magnetic field used in the simulations has a dipole-like symmetry. Contrary to the simulations of the MR core-collapse model with an initial quadrupole-like magnetic field, where the matter was ejected mainly near the equatorial plane, in the presence of the dipole-like initial magnetic field the core-collapse model explosion is developing preferably along a rotational axis and leads to the formation of a protojet. We expect that protojet propagation through the envelope of the star will be accompanied by its collimation. The magnetorotational instability (MRI) was found in the simulations, similar to the earlier considered case of the quadrupole-like initial magnetic field. Our estimations show that the characteristic time for the reconnection of the magnetic field is much larger than the MRI development time. The supernova explosion energy for the dipole-like field is about 0.61 × 1051 erg, and about 0.13 M⊙ of mass was ejected during the explosion.
Monthly Notices of the Royal Astronomical Society 07/2006; 370(1):501 - 512. · 4.90 Impact Factor
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ABSTRACT: We present results of 2D simulation of magnetorotational (MR) supernova accompanied by jet formation in the core collapse supernova explosion. Initial magnetic field used in the simulations has dipole-like symmetry. Contrary to the simulations of MR supernova with initial quadrupole-like magnetic field, where the matter was ejected mainly near the equatorial plane, in presence of the dipole-like initial magnetic field the supernova explosion is developing preferably along a rotational axis, and leads to formation of a protojet. We expect that protojet propagation through the envelope of the star will be accompanied by its collimation. The magnetorotational instability (MRI) was found in simulations, similar to the earlier considered case of the quadrupole-like initial magnetic field. Our estimations show that the characteristic time for the reconnection of the magnetic field is much larger than the MRI development time. The supernova explosion energy for the dipole-like field is about $0.61\cdot 10^{51}$erg, and about $0.13M_\odot$ of mass was ejected during the explosion.
04/2006;
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ABSTRACT: Core-collapse supernovae are connected with formation of neutron stars. Part of the gravitation energy is transformed into the energy of the explosion, observed in SN II, SN Ib,c type supernovae. The mechanism of transformation is not simple, because the overwhelming majority of the energy is going into weakly interacting neutrino. The attempts to use this energy for the explosion were not successful during about 40 years of investigation. We consider the explosion mechanism in which the source of energy is the rotation, and magnetic field serves for the transformation of the rotation energy into the energy of explosion. 2-D MHD simulations of this mechanism were performed. After the collapse the core consists of a rapidly rotating proto-neutron star with a differentially rotating envelope. The toroidal part of the magnetic energy generated by the differential rotation grows as quadratic function with time at the initial stage of the evolution of the magnetic field. The linear growth of the toroidal magnetic field is terminated by the development of magnetohydrodynamic instability, when the twisted toroidal component strongly exceeds the poloidal field, leading to a drastic acceleration in the growth of magnetic energy. At the moment when the magnetic pressure becomes comparable to the gas pressure at the periphery of the proto-neutron star the MHD compression wave appears and goes through the envelope of the collapsed core. It transforms into the fast MHD shock and produces a supernova explosion. Our simulations give the energy of the explosion $0.6\cdot 10^{51}$ ergs. The amount of the mass ejected by the explosion is $\sim 0.14M_\odot$. The implicit numerical method, based on the Lagrangian triangular grid of variable structure, was used for the simulations.
12/2005;
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ABSTRACT: We present the results of two-dimensional simulations of the magnetorotational model of a supernova explosion. After the core collapse, the core consists of a rapidly rotating protoneutron star and a differentially rotating envelope. The toroidal part of the magnetic energy generated by the differential rotation grows linearly with time at the initial stage of the evolution of the magnetic field. The linear growth of the toroidal magnetic field is terminated by the development of magnetorotational (MRI) instability, leading to drastic acceleration in the growth of magnetic energy. At the moment when the magnetic pressure becomes comparable with the gas pressure at the periphery of the protoneutron star ∼10–15 km from the star centre, the magnetohydrodynamic (MHD) compression wave appears and goes through the envelope of the collapsed iron core. It transforms soon to the fast MHD shock and produces a supernova explosion. Our simulations give the energy of the explosion 0.6 × 1051 erg. The amount of the mass ejected by the explosion is ∼0.14 M⊙. The implicit numerical method, based on the Lagrangian triangular grid of variable structure, was used for the simulations.
Monthly Notices of the Royal Astronomical Society 04/2005; 359(1):333 - 344. · 4.90 Impact Factor
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ABSTRACT: Results of 2D simulations of the magnetorotational mechanism of supernova type II are presented. Amplification of toroidal
magnetic field of the star due to differential rotation of the star leads to the transformation of the rotational (gravitational)
energy to the energy of the supernova explosion. In our simulation the energy of the explosion is 1.12 × 1051 erg. The explosion ejects about 0.11 M⨀.
12/2004: pages 281-285;
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ABSTRACT: We present 2D results of simulations of the magnetorotational core collapsed supernova. For the first time we obtain strong explosion for the core collapsed supernova. In 2D approximation we show that amplification of the toroidal magnetic field due to the differential rotation leads to the formation of MHD shockwave, which produces supernova explosion. The amounts of the ejected mass $0.1M_\odot$ and energy $\sim 0.5\div0.6 \cdot 10^{51}$ergs can explain the energy output for supernova type II or type Ib/c explosions. The shape of the explosion is qualitatively depends on the initial configuration of the magnetic field, and may form strong ejection neat the equatorial plane, or produce mildly collimated jets. Our simulation show that during the evolution of the magnetic field the magnetorotational instability appears and leads to exponential growth of the magnetic field strength.
11/2004;
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ABSTRACT: Results are presented from a two-dimensional numerical simulation of the collapse of a rotating core with formation of a neutron star that has strong differential rotation in its outer regions. A specially developed numerical method is used which is based on a fully conservative implicit operator difference scheme for gravitational gas dynamics problems in lagrangian coordinates on a variable-structure triangular grid. The recoil shock wave generated by the collapse causes ejection of a small amount of material. This cannot explain the explosion of type II supernovae. The strong differential rotation in the presence of even a weak initial magnetic field obtained in these calculations must lead to a rise in the magnetic pressure, formation of an MHD shock wave, and conversion of rotational energy into the energy of radial expansion (magnetorotational supernova explosion).
Astrophysics 12/2003; 47(1):37-51. · 0.47 Impact Factor
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ABSTRACT: Results of 2D simulations of the magnetorotational mechanism of supernova type II are presented. Amplification of toroidal magnetic field of the star due to differential rotation of the star leads to the transformation of the rotational (gravitational) energy to the energy of the supernova explosion. In our simulation the energy of the explosion is $1.12 \cdot 10^{51}erg$. The explosion ejects about $0.11 M_\odot$.
11/2003;
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ABSTRACT: The magnetorotational mechanism for supernova type II explosions is investigated numerically in 2-D. For the simulations we use a specially developed, implicit Lagrangian method on a triangular grid with grid reconstruction. We show that the shape of the explosion qualitatively depends on the initial configuration of the poloidal magnetic field. We also have done simulations of the problem of collapse of the protoneutron star. It was shown that after the collapse the resulting configuration consists of a dense, almost rigid, rapidly rotating core and a prolate, slowly rotating envelope. The angular velocity changes very quickly in the transitional region between the core and the envelope. In such a situation we can expect rapid evolution of the toroidal component of the magnetic field due to di#erential rotation, which can lead to the explosion.
03/2003;
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Revista Mexicana de Astronomía y Astrofísica. 01/2003;
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ABSTRACT: Jet formation is connected most probably with matter acceleration from the vicinity of rotating magnetized bodies. It is usually related to the mass outflows and ejection from accretion disks around black holes. Problem of jet collimation is discussed. Collapse of a rotating magnetized body during star formation or supernovae explosion may lead to a jet-like mass ejection for certain angular velocity and magnetic field distributions at the beginning of the collapse. Jet formation during magnetorotational explosion is discussed basing on the numerical simulation of collapse of magnetized bodied with quasi-dipole field. Comment: Will be published in the proc. of 20th Texas Symposium, Austin, Texas 7 pages, 7 pictures
04/2001;
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ABSTRACT: We present results of the 2D simulations of magnetorotational mechanism for the rotating magnetized cloud. It was found that
amplification of the toroidal magnetic field leads to the transformation of the part of the rotational energy of the cloud
to the kinetic energy of radial motion. A compression wave appearing in the transition region between the core of the cloud
and the envelope transforms soon to the MHD shock wave and pushes away part of the envelope of the cloud. Time evolution of
the thrown away mass and energy are given. Simulations have been made on the base of the conservative implicit Lagrangian
scheme on triangular grid with grid reconstruction.
Astrophysics and Space Science 09/2000; 274(1):389-397. · 1.69 Impact Factor
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ABSTRACT: We perform 2D numerical simulations of a magnetorotational explosion of a rotating magnetized gas cloud. We found that amplification of a toroidal magnetic field due to the differential rotation leads to a transformation of the part of the rotational energy of the cloud to the radial kinetic energy. Simulations have been made for 3 initial values of $\xi$ (the relation of magnetic energy to the gravitational energy of the cloud): $\xi =10^{-2},10^{-4},10^{-6}$. Part of the matter - $\sim 7%$ of the mass of the cloud ($\sim 3.3%$ of the final gravitational energy of the cloud) - gets radial kinetic energy which is larger than its potential energy and can be thrown away to the infinity. It carries about 30% of the initial angular momentum of the cloud. This effect is important for angular momentum loss in the processes of stellar formation, and for the magnetorotational mechanism of explosion suggested for supernovae. Simulations have been made on the basis of the Lagrangian 2D numerical implicit scheme on a triangular grid with grid reconstruction.
01/2000;
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ABSTRACT: We present results of 2D simulation of the magnetorotational supernova
explosion. Simulation has been done using implicit Lagrangian scheme on
triangular grig with grid reconstruction. Amplification of the toroidal
magnetic field due to the differential rotation in the star leads to the
formation of the of compression wave moving outwars. This wave
transforms to the shock wave and ejects part of the envelope. Time
evolution of the amount of the ejected mass and ejected energy are
given.
11/1998; -1:460.
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ABSTRACT: Results of 2D numerical simulation of magnetorotational mechanism of supernova explosion are presented. It is shown that due to the differential rotation of the star toroidal component of magnetic field appears and grows with time. Angular momentum transfers outwards by the toroidal magnetic field. With the evolution of the process part of the envelope of the star is throwing away. The amount of thrown away mass and energy are estimated. The results of the simulation are qualitatively correspond to supernova explosion picture.
08/1997;
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ABSTRACT: 2D numerical simulation of the collapse of a rotating magnetized cloud has been done as preliminary investigation of the magnetorotational mechanism of a supernova explosion. Part of the cloud envelope is ejected when magnetic pressure becomes comparable with gas pressure. The mass of the envelope ejected and the energy it carries away are estimated.
Astrophysics and Space Science 04/1996; 239(1):1-13. · 1.69 Impact Factor
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ABSTRACT: An implicit Lagrangian method based on a triangular grid is developed
here for calculations of nonstationary astrophysical processes including
collapse of rotating clouds in the first stages of star formation and
models of supernova explosions in rotating stars. We restrict ourselves
to the development of a reliable hydrodynamical numerical scheme with
self-gravitation and use only simple equations of state without thermal
processes, with entropy changing only in the shocks. The quality of the
method is demonstrated on several test problems. The main application of
the method is to the collapse of a rapidly rotating gas cloud. This
problem has been investigated by many authors with the same physical
conditions. We have obtained results for the stages of the collapse up
to secondary compression and discuss their reliability in comparison
with previous authors. Our results are in qualitative accordance with
others obtained by Lagrangian methods, while we extending the
calculations farther. We do not confirm the formation of a ring
structure obtained by use of Eulerian schemes.
Astronomy and Astrophysics Supplement Series 01/1996; 115:573-594.
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ABSTRACT: Our 2D simulations of the magnetorotational mechanism (MRM) of the ex-plosions of the core collapse supernovae show that MRM produces enough energy for the explanation of such supernova (0.5 − 0.6 × 10 51 erg). The amplification of the magnetic field due to the differential rotation leads to formation of the MHD shock. The "shape" of the su-pernova explosion depends qualitatively on the symmetry type of the initial magnetic field. The magnetorotational instability (MRI) was found in the simulations which significantly reduces the evolution time of the magnetic field amplification. The MRM can produce one sided jets and kicks. For the simulations we have used a specially developed numerical method based on the completely conservative implicit Lagrangian numerical scheme on the triangular Lagrangian grid of a variable structure.
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Proceedings of the International Astronomical Union 214:117.
