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Parker instability leads to the formation of tangential discontinuities in a magnetic field and subsequent magnetic reconnection due to a numerical and/or an explicit resistivity. In this paper we investigate the role of the uniform,…

Astrophysics · Physics 2009-11-07 Grzegorz Kowal , Michal Hanasz , Katarzyna Otmianowska-Mazur

The role of magnetic fields in galaxy evolution is still an unsolved question in astrophysics. We have previously shown that magnetic fields play a crucial role in major mergers between disc galaxies; in hydrodynamic simulations of such…

Astrophysics of Galaxies · Physics 2023-09-28 Joseph Whittingham , Martin Sparre , Christoph Pfrommer , Rüdiger Pakmor

The physical modeling of the accretion disk boundary layer, the region where the disk meets the surface of the accreting star, usually relies on the assumption that angular momentum transport is opposite to the radial angular frequency…

High Energy Astrophysical Phenomena · Physics 2012-11-28 Chi-kwan Chan , Martin E. Pessah

Structure of a quasi-stationary stellar cluster is modelled assuming that it is embedded in the gravitational field of a super-massive black hole. Gradual orbital decay of stellar trajectories is caused by the dissipative interaction with…

Astrophysics · Physics 2007-05-23 L. Subr , V. Karas , J. -M. Hure

We study the star-disc interaction in the presence of the strong magnetic field ($B_\star=6.2kG$) of a slowly rotating star. This situation describes a post-merger of the spectral type B and has not been previously investigated. We perform…

Solar and Stellar Astrophysics · Physics 2024-02-08 A. Moranchel-Basurto , D. Korčáková , R. O. Chametla

We present a set of global, self-consistent N-body/SPH simulations of the dynamic evolution of galactic discs with gas and including magnetic fields. We have implemented a description to follow the evolution of magnetic fields with the…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-13 H. Kotarba , H. Lesch , K. Dolag , T. Naab , P. H. Johansson , F. A. Stasyszyn

We describe a three-dimensional, Godunov-type numerical magnetohydrodynamics (MHD) method designed for studying disk accretion to a rotating magnetized star in the general case where the star's rotation axis, its magnetic moment, and the…

Astrophysics · Physics 2009-11-07 A. V. Koldoba , M. M. Romanova , G. V. Ustyugova , R. V. E. Lovelace

We studied the collapse of rotating molecular cloud cores with inclined magnetic fields, based on three-dimensional numerical simulations.The numerical simulations start from a rotating Bonnor-Ebert isothermal cloud in a uniform magnetic…

Astrophysics · Physics 2009-11-11 Masahiro N. Machida , Tomoaki Matsumoto , Tomoyuki Hanawa , Kohji Tomisaka

It appears that most stars are born in clusters, and that at birth most stars have circumstellar discs which are comparable in size to the separations between the stars. Interactions between neighbouring stars and discs are therefore likely…

Astrophysics · Physics 2015-06-24 H. M. J. Boffin , S. J. Watkins , A. S. Bhattal , N. Francis , A. P. Whitworth

The problem of the late accretion phase of the evolution of an axisymmetric, isothermal magnetic disk surrounding a forming star has been formulated in a companion paper. The "central sink approximation" is used to circumvent the problem of…

Astrophysics · Physics 2009-11-10 Konstantinos Tassis , Telemachos Ch. Mouschovias

Violent gravitational interactions can change the morphologies of galaxies and, by means of merging, transform them into elliptical galaxies. We aim to investigate how they affect the evolution of galactic magnetic fields. We selected 16…

Cosmology and Nongalactic Astrophysics · Physics 2011-09-23 Robert T. Drzazga , Krzysztof T. Chyzy , Wojciech Jurusik , Krzysztof Wiorkiewicz

The stresses produced by magnetorotational turbulence can provide effective angular momentum transport in accretion disks. However, questions remain about the ability of simulated disks to reproduce observationally inferred…

High Energy Astrophysical Phenomena · Physics 2015-06-19 E. R. Parkin

We present results of axisymmetic magnetohydrodynamic simulations of the interaction of a rapidly-rotating, magnetized star with an accretion disk. The disk is considered to have a finite viscosity and magnetic diffusivity. The main…

Astrophysics · Physics 2009-11-11 G. V. Ustyugova , A. V. Koldoba , M. M. Romanova , R. V. E. Lovelace

We use a 3D radiative non-ideal magnetohydrodynamic (MHD) simulation to investigate the formation and evolution of a young protostellar disc from a magnetized pre-stellar core. The simulation covers the first ${\sim}10~{\rm kyr}$ after…

Solar and Stellar Astrophysics · Physics 2021-09-29 Wenrui Xu , Matthew W. Kunz

Using a numerical simulation, we study the effects of ambipolar diffusion and ohmic diffusion on the magnetic field evolution in the interior of an isolated neutron star. We are interested in the behavior of the magnetic field on a long…

Astrophysics · Physics 2008-11-26 Jaime Hoyos , Andreas Reisenegger , Juan A. Valdivia

We use three dimensional magnetohydrodynamic simulations to study the structure of the boundary layer between an accretion disc and a non-rotating, unmagnetized star. Under the assumption that cooling is efficient, we obtain a narrow but…

Astrophysics · Physics 2009-11-07 Philip J. Armitage

The origin and the magnitude of the inter-galactic magnetic field is of primordial importance in the global picture of magnetic field evolution, as it is considered to be the missing link between galactic magnetic fields and cluster…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-14 Yohan Dubois , Romain Teyssier

Interactions between disc-surrounded stars might play a vital role in the formation of planetary systems. Here a first parameter study of the effects of encounters on low-mass discs is presented. The dependence of the mass and angular…

Astrophysics · Physics 2009-11-11 S. Pfalzner , P. Vogel , J. Scharwaechter , C. Olczak

To obtain a simple description of a geometrically thin magnetic accretion disk, we apply the method of asymptotic expansion. For the first time we write a full set of stationary asymptotic approximation equations of a thin magnetic…

Solar and Stellar Astrophysics · Physics 2019-07-31 M. Čemeljić , W. Kluźniak , V. Parthasarathy

The magnetorotational instability (MRI) has been extensively studied in circular magnetized disks, and its ability to drive accretion has been demonstrated in a multitude of scenarios. There are reasons to expect eccentric magnetized disks…

High Energy Astrophysical Phenomena · Physics 2023-12-13 Chi-Ho Chan , Tsvi Piran , Julian H. Krolik