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The properties of the extremely strong magnetic fields of neutron stars affect in a unique way their evolution and the associated phenomenology. Due to the lack of constraints from direct observations, our understanding of the magnetic…

High Energy Astrophysical Phenomena · Physics 2015-06-22 Riccardo Ciolfi

The interaction of a rotating star's magnetic field with a surrounding plasma disk lies at the heart of many questions posed by neutron stars in X-ray binaries. We consider the opening of stellar magnetic flux due to differential rotation…

High Energy Astrophysical Phenomena · Physics 2016-07-14 Kyle Parfrey , Anatoly Spitkovsky , Andrei M. Beloborodov

Many millisecond pulsars are thought to be old neutron stars spun up (`recycled') during an earlier accretion phase. They typically have relatively weak ($\lesssim 10^{9} \text{ G}$) dipole field strengths, consistent with accretion-induced…

High Energy Astrophysical Phenomena · Physics 2020-10-21 Arthur G. Suvorov , Andrew Melatos

We consider generation and evolution of small-scale magnetic fields in neutron stars. These fields can be generated by small-scale turbulent dynamo action soon after the collapse when the proto-neutron star is subject to convective and…

Astrophysics · Physics 2009-11-10 V. Urpin , J. Gil

We develop a new analytic solution for the steady-state structure of a thin accretion disc under the influence of a magnetic field that is anchored to the central star. The solution takes a form similar to that of Shakura and Sunyaev and…

Astrophysics · Physics 2009-11-10 O. M. Matthews , R. Speith , M. R. Truss , G. A. Wynn

We construct general relativistic models of stationary, strongly magnetized neutron stars. The magnetic field configuration, obtained by solving the relativistic Grad-Shafranov equation, is a generalization of the twisted torus model…

Solar and Stellar Astrophysics · Physics 2015-05-18 R. Ciolfi , V. Ferrari , L. Gualtieri

In association with the Goldreich-Julian's magnetic braking mechanism to explain the luminosity of radio pulsars as a result of their spin-down, it is of some interest to explore how much of magnetic flux can actually penetrate the surface…

Astrophysics · Physics 2007-05-23 Hongsu Kim , Hyung Mok Lee , Chul H. Lee , Hyun Kyu Lee

The role of magnetic fields for the formation of planets is reviewed. Protoplanetary disc turbulence driven by the magnetorotational instability has a huge influence on the early stages of planet formation. Small dust grains are transported…

Earth and Planetary Astrophysics · Physics 2015-05-13 Anders Johansen

We study the stability of poloidal magnetic fields anchored in a thin accretion disc. The two-dimensional hydrodynamics in the disc plane is followed by a grid-based numerical simulation including the vertically integrated magnetic forces.…

Astrophysics · Physics 2015-06-24 R. Stehle , H. C. Spruit

The vertical structure of the accretion disks of young stars with fossil large-scale magnetic field is studied. The equations of magnetostatic equilibrium of the disk are solved taking into account the stellar gravity, gas and magnetic…

Solar and Stellar Astrophysics · Physics 2022-10-25 Sergey A. Khaibrakhmanov , Alexander E. Dudorov , Anton I. Vasyunin , Mikhail Yu. Kiskin

Millisecond pulsars are neutron stars (NSs) that are thought to have been spun-up by mass accretion from a stellar companion. It is unknown whether there is a natural brake for this process, or if it continues until the centrifugal breakup…

We review the current status of studies on accretion and protoplanetary disks of young stars with large-scale magnetic fields. Observational data on magnetic fields of the disks are compiled and analysed. Modern analytical and numerical MHD…

Solar and Stellar Astrophysics · Physics 2024-01-26 Sergey A. Khaibrakhmanov

The accretion induced neutron star magnetic field evolution is studied through considering the accretion flow to drag the field lines aside and dilute the polar field strength, and as a result the equatorial field strength increases and is…

Astrophysics · Physics 2009-11-10 C. M. Zhang , Y. Kojima

We present numerical simulations of electron-positron pair cascades in the magnetospheres of magnetic neutron stars for a wide range of surface fields (B_p = 10^{12}--10^{15} G), rotation periods (0.1--10 s), and field geometries. This has…

High Energy Astrophysical Phenomena · Physics 2012-07-31 Zach Medin , Dong Lai

Strong magnetic fields are observed in a substantial fraction of upper main sequence stars and white dwarfs. Many such stars are observed to exhibit photometric modulations as the magnetic poles rotate in and out of view, which could be a…

Solar and Stellar Astrophysics · Physics 2023-02-22 Jim Fuller , Stephane Mathis

Strong magnetic field of accreting neutron stars ($10^{14}$ G) is hard to probe by X-ray spectroscopy but can be indirectly inferred from spin-up/spin-down measurement in X-ray pulsars. The existing observations of slowly rotating X-ray…

High Energy Astrophysical Phenomena · Physics 2015-06-16 K. A. Postnov , N. I. Shakura , A. Yu. Kochetkova , L. Hjalmarsdotter

The effects of magnetic fields on accretion disks around compact objects are of high importance in the study of their general properties and dynamics. Here we analyze the influence of magnetic fields on thick accretion disks around rotating…

General Relativity and Quantum Cosmology · Physics 2023-06-07 Kristian Gjorgjieski , Jutta Kunz , Matheus C. Teodoro , Lucas G. Collodel , Petya Nedkova

The pre-stellar cores in which low mass stars form are generally well magnetized. Our simulations show that early protostellar discs are massive and experience strong magnetic torques in the form of magnetic braking and protostellar…

Solar and Stellar Astrophysics · Physics 2015-05-20 Dennis Duffin , Ralph E. Pudritz

Magnetic fields represent a crucial aspect of the physics and astrophysics of neutron stars. Despite its great relevance, the internal magnetic field configuration of neutron stars is very poorly constrained by the observations, and…

High Energy Astrophysical Phenomena · Physics 2015-06-18 Riccardo Ciolfi

Stellar spin is one of the fundamental quantities that characterize a star itself and its planetary system. Nevertheless, stellar spin-down mechanisms in protostellar and pre-main-sequence stellar phases have been a long-standing problem in…

Solar and Stellar Astrophysics · Physics 2024-12-20 Shinsuke Takasao , Masanobu Kunitomo , Takeru K. Suzuki , Kazunari Iwasaki , Kengo Tomida