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Convection in massive main sequence stars generates large scale magnetic fields in their cores which persists as they evolve up the red giant branch. The remnants of these fields may take the form of the Prendergast magnetic field, a…

Solar and Stellar Astrophysics · Physics 2022-10-12 Emma Kaufman , Daniel Lecoanet , Evan H. Anders , Benjamin P. Brown , Geoffrey M. Vasil , Jeffrey S. Oishi , Keaton J. Burns

The flow of a matter, accreting onto a magnetized neutron star, is accompanied by an electric current. The closing of the electric current occurs in the crust of a neutron stars in the polar region across the magnetic field. But the…

High Energy Astrophysical Phenomena · Physics 2016-04-01 Ya. N. Istomin , I. A. Semerikov

Dynamical instabilities in protoneutron stars may produce gravitational waves whose observation could shed light on the physics of core-collapse supernovae. When born with sufficient differential rotation, these stars are susceptible to a…

In [Gusakov et al.\ PRD, 96, 103012, (2017)], we proposed a self-consistent method to study the quasistationary evolution of the magnetic field in neutron-star cores. Here we apply it to calculate the instantaneous particle velocities and…

High Energy Astrophysical Phenomena · Physics 2018-08-13 D. D. Ofengeim , M. E. Gusakov

Some Ap stars with strong magnetic fields pulsate in high order p-modes; they are called roAp (rapidly oscillating Ap) stars. The p-mode frequencies are modified by the magnetic fields. Although the large frequency separations are hardly…

Solar and Stellar Astrophysics · Physics 2015-06-17 Hideyuki Saio

We study the spindown of isolated neutron stars from initially rapid rotation rates, driven by two factors: (i) gravitational wave emission due to r-modes and (ii) magnetic braking. In the context of isolated neutron stars, we present the…

Solar and Stellar Astrophysics · Physics 2015-05-28 Jan Staff , Prashanth Jaikumar , Vincent Chan , Rachid Ouyed

Stars are self-gravitating fluids in which pressure, buoyancy, rotation and magnetic fields provide the restoring forces for global modes of oscillation. Pressure and buoyancy energetically dominate, while rotation and magnetism are…

Solar and Stellar Astrophysics · Physics 2017-04-19 Shyeh Tjing Loi , John C. B. Papaloizou

We investigate the 50-year old hypothesis that the magnetic fields of the Ap stars are stable equilibria that have survived in these stars since their formation. With numerical simulations we find that stable magnetic field configurations…

Astrophysics · Physics 2009-11-11 J. Braithwaite , A. Nordlund

Millisecond pulsars, with magnetic fields weaker by three to four orders compared to those of ordinary pulsars, are presumed to be neutron stars spun up by binary accretion. We expect the magnetic field to get screened by the accreted…

Astrophysics · Physics 2007-05-23 Arnab Rai Choudhuri , Sushan Konar

Accretion disks are ubiquitous in the universe and it is generally accepted that magnetic fields play a pivotal role in accretion-disk physics. The spin history of millisecond pulsars, which are usually classified as magnetized neutron…

Solar and Stellar Astrophysics · Physics 2013-12-16 Luca Naso , John Miller , Wlodek Kluzniak

There exists both theoretical and observational evidence that the magnetic field decay in neutron stars may proceed in a pronounced non--linear way during a certain episode of the neutron star's life. In the presence of a strong magnetic…

Astrophysics · Physics 2009-11-07 U. Geppert , M. Rheinhardt

There is growing evidence, based on both X-ray and radio observations of isolated neutron stars, that besides the large--scale (dipolar) magnetic field, which determines the pulsar spin--down behaviour, small--scale poloidal field…

Astrophysics · Physics 2009-11-10 U. Geppert , M. Rheinhardt , J. Gil

The axial mode oscillations are examined for relativistic rotating stars with uniform angular velocity. Using the slow rotation formalism and the Cowling approximation, we have derived the equations governing the r-mode oscillations up to…

Astrophysics · Physics 2015-06-24 Yasufumi Kojima , Masayasu Hosonuma

We study the instability of magnetic fields in a neutron star core driven by the parity violating part of the electron-nucleon interaction in the Standard Model. Assuming a seed field of the order $10^{12}\thinspace\text{G}$, that is a…

High Energy Astrophysical Phenomena · Physics 2015-05-20 Maxim Dvornikov , Victor B. Semikoz

We examine the generation of a magnetic field in a solar-like star and its effects on the internal distribution of the angular velocity. We suggest that the evolution of a rotating star with magnetic fields leads to an equilibrium value of…

Astrophysics · Physics 2009-11-11 P. Eggenberger , A. Maeder , G. Meynet

The processes contributing to the evolution of an initially weak magnetic field in a differentially rotating star are reviewed. These include rotational smoothing (akin to convective expulsion) and a list of about 5 instabilities, among…

Astrophysics · Physics 2007-05-23 H. C. Spruit

The intense magnetic fields present in neutron stars are closely linked to their observed temperature and spectral characteristics, timing properties, including spin period and its derivatives. Therefore, a comprehensive theoretical…

High Energy Astrophysical Phenomena · Physics 2025-02-03 Debasis Atta , Vinay Singh , D. N. Basu

Magnetic fields have been observed in massive Ap/Bp stars and presumably are also present in the radiative zone of solar-like stars. Yet, to date there is no clear understanding of the dynamics of the magnetic field in stably stratified…

Solar and Stellar Astrophysics · Physics 2023-03-27 G. Monteiro , G. Guerrero , F. Del Sordo , A. Bonanno , P. K. Smolarkiewicz

We have investigated an influence of the r-mode instability on hypercritically accreting ($\dot{M}\sim 1M_\odot {y}^{-1}$) neutron stars in close binary systems during their common envelope phases based on the scenario proposed by Bethe et…

Astrophysics · Physics 2010-11-19 Shin'ichirou Yoshida , Yoshiharu Eriguchi

We briefly review the turbulent mean-field dynamo action in protoneutron stars that are subject to convective and neutron finger instabilities during the early evolutionary phase. By solving the mean-field induction equation with the…

High Energy Astrophysical Phenomena · Physics 2011-01-11 Alfio Bonanno , Vadim Urpin