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Neutron stars are not observed to spin faster than about half their breakup rate. This limiting rotational frequency may be related to the strength of their crusts. As a star spins up from accretion, centrifugal forces stress the crust. We…

High Energy Astrophysical Phenomena · Physics 2024-12-17 J. A. Morales , C. J. Horowitz

We present the results of 3--D nonlinear simulations of magnetic dynamo action by core convection within A-type stars of 2 solar masses, at a range of rotation rates. We consider the inner 30% by radius of such stars, with the spherical…

Astrophysics · Physics 2009-11-10 Matthew Browning , Allan Sacha Brun , Juri Toomre

We study the effects of rotation on the torsional modes of oscillating relativistic stars with a solid crust. Earlier works in Newtonian theory provided estimates of the rotational corrections for the torsional modes and suggested that they…

General Relativity and Quantum Cosmology · Physics 2008-11-26 M. Vavoulidis , A. Stavridis , K. D. Kokkotas , H. Beyer

A simplified model for stellar and planetary convection is derived for the magnitude of the rms velocity, degree of superadiabaticity, and characteristic length scale with Rossby number as well as with thermal and viscous diffusivities.…

Solar and Stellar Astrophysics · Physics 2018-11-13 Kyle Augustson , Stéphane Mathis

We calculate moment of inertia of neutron star with different exotic constituents such as hyperons and (anti)kaon condensates and study its variation with mass and spin frequency. The sets of equation of state, generated within the…

High Energy Astrophysical Phenomena · Physics 2017-06-14 S. S. Lenka , P. Char , S. Banik

Using time evolutions of the relevant linearised equations we study non-axisymmetric oscillations of rapidly rotating and superfluid neutron stars. We consider perturbations of Newtonian axisymmetric background configurations and account…

Astrophysics · Physics 2009-11-13 Andrea Passamonti , Brynmor Haskell , Nils Andersson

Neutron stars are compact objects rotating at high speed, up to a substantial fraction of the speed of light (up to 20\% for millisecond pulsars) and possessing ultra-strong electromagnetic fields (close to and sometimes above the quantum…

High Energy Astrophysical Phenomena · Physics 2020-01-13 Jérôme Pétri

Superfluid hydrodynamics affects the spin-evolution of mature neutron stars, and may be key to explaining timing irregularities such as pulsar glitches. However, most models for this phenomenon exclude the global instability required to…

Solar and Stellar Astrophysics · Physics 2013-03-27 N. Andersson , K. Glampedakis , M. Hogg

We consider static neutron stars within the framework of $R^2$ gravity. The neutron fluid is described by three different types of realistic equations of state (soft, moderately stiff, and stiff). Using the observational data on the neutron…

General Relativity and Quantum Cosmology · Physics 2018-06-08 Vladimir Folomeev

We present an analytic description of the $r$-mode instability in newly-born neutron stars, using the approximation of uniform density. Our computation is consistently accurate to second order in the angular velocity of the star. We obtain…

Astrophysics · Physics 2011-05-23 K. D. Kokkotas , N. Stergioulas

The gravitational properties of astrophysical objects depend sensitively on their internal structure. In Newtonian theory, the gravitational potential of a rotating star can be fully described by an infinite number of multipole moments of…

General Relativity and Quantum Cosmology · Physics 2014-10-01 Katerina Chatziioannou , Kent Yagi , Nicolas Yunes

The presence of a viscous boundary layer under the solid crust of a neutron star dramatically increases the viscous damping rate of the fluid r-modes. We improve previous estimates of this damping rate by including the effect of the…

Astrophysics · Physics 2009-10-31 Lee Lindblom , Benjamin J. Owen , Greg Ushomirsky

This paper presents the results of a set of radiative hydrodynamic (RHD) simulations of convection in the near-surface regions of a rapidly rotating star. The simulations use microphysics consistent with stellar models, and include the…

Solar and Stellar Astrophysics · Physics 2020-06-10 Frank Robinson , Joel Tanner , Sarbani Basu

It has been recently argued through numerical work that rotating stars with a high degree of differential rotation are dynamically unstable against bar-mode deformation, even for values of the ratio of rotational kinetic energy to…

Astrophysics · Physics 2009-06-23 Pablo Cerdá-Durán , Vicent Quilis , José A. Font

The evolution of a neutron-star r-mode driven unstable by gravitational radiation (GR) is studied here using numerical solutions of the full non-linear fluid equations. The amplitude of the mode grows to order unity before strong shocks…

Astrophysics · Physics 2009-10-31 Lee Lindblom , Joel E. Tohline , Michele Vallisneri

Three-dimensional, Gross-Pitaevskii equation (GPE) simulations are presented of the interaction between neutron superfluid vortices and proton superconductor flux tubes in a rotating, harmonic trap, representing an idealised model of the…

High Energy Astrophysical Phenomena · Physics 2017-09-08 L. V. Drummond , A. Melatos

In this work, we study the impact of anisotropy on slowly rotating neutron stars by extending the Hartle-Thorne formalism in general relativity to include anisotropy in pressure up to second order in the angular velocity. We assess the…

General Relativity and Quantum Cosmology · Physics 2024-10-10 L. M. Becerra , E. A. Becerra-Vergara , F. D. Lora-Clavijo

Neutron stars exhibit magnetic fields and densities far beyond those achievable in terrestrial laboratories, offering a natural probe of strongly interacting matter under extreme conditions. Using observationally anchored mass-radius…

Cosmology and Nongalactic Astrophysics · Physics 2026-01-13 Abriana Lyda , Prajwal MohanMurthy

Our recent Newtonian treatment of the smooth-averaged mutual-friction force acting on the neutron superfluid and locally induced by the pinning of quantized neutron vortices to proton fluxoids in the outer core of superfluid neutron stars…

High Energy Astrophysical Phenomena · Physics 2021-03-17 Aurélien Sourie , Nicolas Chamel

We present several exact solutions of the eigenfrequency problem for torsional shear vibrations in homogeneous and non-homogeneous models of the neutron star crust governed by canonical equation of solid mechanics with a restoring force of…

Astrophysics · Physics 2009-11-13 S. I. Bastrukov , H. -K. Chang , J. Takata , G. -T. Chen , I. V. Molodtsova