Axisymmetric and stationary magnetic field structures in neutron star crusts under various boundary conditions

AbstractWe have calculated many Hall equilibrium states within the neutron star crust under various boundary conditions in order to investigate the influences of the boundary conditions clearly. We have found two important features of these solutions. First, the magnitude of the core magnetic fields affects the toroidal to total magnetic field energy ratio within the crust (Et/E). If the core magnetic fields are vanished, the crustal toroidal magnetic fields become weak and the typical energy ratio is only Et / E ~ 0.1%. If the core magnetic fields are strong, however, the crustal toroidal magnetic fields become strong and the typical ratio reaches Et / E ~ 15%. Second, the core toroidal magnetic fields and the twisted magnetosphere around the star make the size of the crustal toroidal magnetic field regions large. Therefore if the strong core magnetic fields have strong toroidal component, both strength and size of the crustal toroidal magnetic fields become large. These results show that the Hall MHD evolutions would be deeply affected by both inner and outer boundary conditions.

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On the Nature of Magnetars

Symposium - International Astronomical Union ◽

10.1017/s0074180900181124 ◽

2004 ◽

Vol 218 ◽

pp. 265-266

Author(s):

Ya. N. Istomin

Keyword(s):

Magnetic Field ◽

Neutron Star ◽

Magnetic Fields ◽

Electromagnetic Fields ◽

Gamma Ray ◽

X Ray ◽

Surface Magnetic Field ◽

The Core ◽

Neutron Star Crust ◽

High Magnitude

The electromagnetic fields of magnetodipole radiation can penetrate to the conducting matter of a neutron star crust and create there electric currents and tangential magnetic fields of high magnitude. The solution obtained here has the form of surface magnetic field discontinuities propagating through the crust to the core. This model explains the phenomena of magnetars — Soft Gamma-ray Repeaters and Anomalous X-ray Pulsars.

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Direct transformation of magnetic-field energy into energy of fast particles

Symposium - International Astronomical Union ◽

10.1017/s007418090010083x ◽

1967 ◽

Vol 31 ◽

pp. 133-134

Author(s):

S. I. Syrovatskii

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Field Energy ◽

Direct Transformation ◽

Magnetic Field Energy ◽

Strongly Connected

There are two distinct but as it seems strongly connected problems. The first is the surprisingly rapid dissipation of magnetic fields which is observed in the Sun's atmosphere and must be supposed for some other objects as well. The second problem is the acceleration of fast particles in magnetized cosmical plasma.

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Magnetic field structures inside magnetars with strong toroidal field

Proceedings of the International Astronomical Union ◽

10.1017/s1743921314002658 ◽

2013 ◽

Vol 9 (S302) ◽

pp. 423-426

Author(s):

Kotaro Fujisawa

Keyword(s):

Magnetic Field ◽

Magnetic Fields ◽

Current Density ◽

Field Configuration ◽

Toroidal Magnetic Field ◽

Field Energy ◽

Equilibrium Studies ◽

Magnetic Field Energy ◽

Negative Current ◽

Magnetic Field Region

AbstractWe have analyzed the magnetized equilibrium studies with strong toroidal magnetic fields and found that the negative toroidal current density inside the star is very important for the strong toroidal magnetic fields. The strong toroidal magnetic fields require the strong poloidal current, but the strong poloidal current results in the localized strong toroidal current density in the axisymmetric system. This localized toroidal current changes the magnetic field configuration and makes the size of the toroidal magnetic field region smaller. As a result, the toroidal magnetic field energy can not become large. We need to cancel out the localized toroidal current density in order to obtain the large toroidal fields solutions. We have found and showed that the negative toroidal current cancels out the localized toroidal current density and sustain the large toroidal magnetic field energy inside the star. We can explain the magnetized equilibrium studies with strong toroidal magnetic fields systematically using the negative current density. Physical meaning of the negative current is key to the magnetar interior magnetic fields.

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An Analytical Solution of the Problem of Plasma Ejection from the Magnetosphere of an Axisymmetric Rotator

International Astronomical Union Colloquium ◽

10.1017/s000273160015526x ◽

1992 ◽

Vol 128 ◽

pp. 245-247

Author(s):

S. V. Bogovalov

Keyword(s):

Magnetic Field ◽

Neutron Star ◽

Analytical Solution ◽

Toroidal Magnetic Field ◽

Field Energy ◽

Crab Pulsar ◽

Plasma Energy ◽

Light Cylinder ◽

Magnetic Field Energy

AbstractThe flow of e+e− plasma ejected by an axisymmetrically rotating magnetized neutron star is considered in a hydrodynamical approximation. It is shown that in the vicinity of the light cylinder a helical discontinuity is formed. The transformation of toroidal magnetic field energy into plasma energy takes place at this discontinuity. Particles are accelerated to an energy of 10TeV for a neutron star with the characteristics of the Crab pulsar.

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Investigation of heat transfer in irregular porous cavity subjected to various boundary conditions

International Journal of Numerical Methods for Heat &amp Fluid Flow ◽

10.1108/hff-04-2018-0132 ◽

2019 ◽

Vol 29 (1) ◽

pp. 418-447 ◽

Cited By ~ 36

Author(s):

Irfan Anjum Badruddin

Keyword(s):

Heat Transfer ◽

Boundary Conditions ◽

Outer Boundary ◽

Governing Equations ◽

Content Type ◽

Porous Cavity ◽

Various Boundary Conditions ◽

Heating Source ◽

Transfer Behavior ◽

Vertical Walls

Purpose The purpose of this paper is to investigate the heat transfer in an arbitrary cavity filled with porous medium. The geometry of the cavity is such that an isothermal heating source is placed centrally at the bottom of the cavity. The height and width of the heating source is varied to analyses its effect on the heat transfer characteristics. The investigation is carried out for three different cases of outer boundary conditions such as two outside vertical walls being maintained at cold temperature To, two vertical and top horizontal surface being heated to. To and the third case with top surface kept at To but other surfaces being adiabatic. Design/methodology/approach Finite element method is used to solve the governing equations. Findings It is observed that the cavity exhibits unique heat transfer behavior as compared to regular cavity. The cases of boundary conditions are found to affect the heat transfer rate in the porous cavity. Originality/value This is original work representing the heat transfer in irregular porous cavity with various boundary conditions. This work is neither being published nor under review in any other journal.

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Analytical solution for buckling of orthotropic double-layered graphene sheets exposed to unidirectional in-plane magnetic field with various boundary conditions

Composites Part B Engineering ◽

10.1016/j.compositesb.2017.12.054 ◽

2018 ◽

Vol 142 ◽

pp. 9-23 ◽

Cited By ~ 8

Author(s):

Nebojša Radić ◽

Dejan Jeremić

Keyword(s):

Magnetic Field ◽

Analytical Solution ◽

Boundary Conditions ◽

Graphene Sheets ◽

Various Boundary Conditions

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The growth of magnetic field energy in conducting fluids

Computational Fluid and Solid Mechanics 2003 ◽

10.1016/b978-008044046-0.50245-1 ◽

2003 ◽

pp. 1004-1007

Author(s):

Philip Livermore ◽

Andrew Jackson

Keyword(s):

Magnetic Field ◽

Field Energy ◽

Magnetic Field Energy ◽

Conducting Fluids

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Onset of superconductivity and retention of magnetic fields in cooling neutron stars

Proceedings of the International Astronomical Union ◽

10.1017/s174392131700970x ◽

2017 ◽

Vol 13 (S337) ◽

pp. 213-216

Author(s):

Wynn C. G. Ho ◽

Nils Andersson ◽

Vanessa Graber

Keyword(s):

Magnetic Field ◽

Neutron Star ◽

Magnetic Fields ◽

Neutron Stars ◽

Minimum Energy ◽

Meissner Effect ◽

Energy Conditions ◽

Field Diffusion ◽

Neutron Star Cooling ◽

Proton Pairing

AbstractA superconductor of paired protons is thought to form in the core of neutron stars soon after their birth. Minimum energy conditions suggest that magnetic flux is expelled from the superconducting region due to the Meissner effect, such that the neutron star core retains or is largely devoid of magnetic fields for some nuclear equation of state and proton pairing models. We show via neutron star cooling simulations that the superconducting region expands faster than flux is expected to be expelled because cooling timescales are much shorter than timescales of magnetic field diffusion. Thus magnetic fields remain in the bulk of the neutron star core for at least 106 − 107yr. We estimate the size of flux free regions at 107yr to be ≲ 100m for a magnetic field of 1011G and possibly smaller for stronger field strengths.

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