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Radial pulsations of newborn neutron stars (protoneutron stars) are studied for a range of internal temperatures and entropies per baryon predicted by the existing numerical simulations. Protoneutron star models are constructed using a…

Astrophysics · Physics 2008-11-26 D. Gondek , P. Haensel , J. L. Zdunik

We investigate the equilibrium and radial stability of spherically symmetric relativistic stars, considering a polytropic equation of state (EoS), within the framework of $f(R,T)$ gravity with a conservative energy-momentum tensor. Both…

General Relativity and Quantum Cosmology · Physics 2021-08-26 Juan M. Z. Pretel , Sergio E. Jorás , Ribamar R. R. Reis , José D. V. Arbañil

The evolution of a nonaxisymmetric bar-mode perturbation of rapidly rotating stars due to a secular instability induced by gravitational wave emission is studied in post-Newtonian simulations taking into account gravitational radiation…

Astrophysics · Physics 2010-11-19 Masaru Shibata , Sigeyuki Karino

Nowadays, many extrasolar planetary systems possessing at least one planet on a highly eccentric orbit have been discovered. In this work, we study the possible long-term stability of such systems. We consider the general three body problem…

Earth and Planetary Astrophysics · Physics 2016-12-09 Kyriaki I. Antoniadou , George Voyatzis

We perform simulations of relativistic binary stars in post-Newtonian gravity to investigate their dynamical stability prior to merger against gravitational collapse in a tidal field. In general, our equations are only strictly accurate to…

General Relativity and Quantum Cosmology · Physics 2009-12-30 M. Shibata , T. W. Baumgarte , S. L. Shapiro

Vector boson stars, also known as Proca stars, exhibit remarkable dynamical robustness, making them strong candidates for potential astrophysical exotic compact objects. In search of theoretically well-motivated Proca star models, we…

General Relativity and Quantum Cosmology · Physics 2025-11-05 Claudio Lazarte , Nicolas Sanchis-Gual , José A. Font , Miguel Alcubierre

The stability of the recently proposed static solutions for boson stars is analyzed. These solutions of Einstein-Klein-Gordon (EKG) equations arise from considering the interaction of a real scalar field with matter. We assume that the…

General Relativity and Quantum Cosmology · Physics 2021-01-14 D. S. Fontanella , A. Cabo

Using general-relativistic hydrodynamical simulations, we show that merging binary neutron stars can form hypermassive neutrons stars that undergo the one-arm spiral instability. We study the particular case of a dynamical capture merger…

High Energy Astrophysical Phenomena · Physics 2016-01-06 Vasileios Paschalidis , William E. East , Frans Pretorius , Stuart L. Shapiro

The stability of a recently proposed general relativistic model of galaxies is studied in some detail. This model is a general relativistic version of the well known Miyamoto-Nagai model that represents well a thick galactic disk. The…

General Relativity and Quantum Cosmology · Physics 2009-11-13 Maximiliano Ujevic , Patricio S. Letelier

This work develops the dynamics of perfectly elastic solid model for application to the outer crust of a magnetised neutron star. Particular attention is given to the Noether identities responsible for energy-momentum conservation, using a…

General Relativity and Quantum Cosmology · Physics 2009-11-11 Brandon Carter , Elie Chachoua , Nicolas Chamel

We study non-axisymmetric oscillations of rapidly and differentially rotating relativistic stars in the Cowling approximation. Our equilibrium models are sequences of relativistic polytropes, where the differential rotation is described by…

Solar and Stellar Astrophysics · Physics 2010-04-22 Christian Krüger , Erich Gaertig , Kostas D. Kokkotas

A set of theoretical mass-radius relations for rigidly rotating neutron stars with exotic cores, obtained in various theories of dense matter, is reviewed. Two basic observational constraints are used: the largest measured rotation…

High Energy Astrophysical Phenomena · Physics 2016-04-20 P. Haensel , M. Bejger , M. Fortin , J. L. Zdunik

In this lecture, we give a first introduction to neutron stars, based on fundamental physical principles. After outlining their outstanding macroscopic properties, as obtained from observations, we infer the extreme conditions of matter in…

High Energy Astrophysical Phenomena · Physics 2016-09-27 Pierre M. Pizzochero

Non-radial oscillation modes of a neutron star possess valuable information about its internal structure and nuclear physics. Starting from the quadrupolar order, such modes under general relativity are known as quasi-normal modes since…

General Relativity and Quantum Cosmology · Physics 2024-11-22 Shu Yan Lau , Siddarth Ajith , Victor Guedes , Kent Yagi

Starting from the assumption that general relativity might be an emergent phenomenon showing up at low-energies from an underlying microscopic structure, we re-analyze the stability of a static closed Universe filled with radiation. In this…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Carlos Barcelo , Grigory Volovik

Properties, structure, and thermal evolution of neutron stars are determined by the equation of state of stellar matter. Recent data on isospin-diffusion and isoscaling in heavy-ion collisions at intermediate energies as well as the size of…

Astrophysics · Physics 2009-11-13 Plamen G. Krastev , Bao-An Li , Aaron Worley

We perform fully general relativistic simulations of rotating stellar core collapse in three spatial dimension. A parametric equation of state is adopted following Dimmelmeier et al. The early stage of the collapse is followed by an…

Astrophysics · Physics 2008-11-26 Masaru Shibata , Yu-ichirou Sekiguchi

We report on general relativistic calculations of quasiequilibrium configurations of binary neutron stars in circular orbits with zero vorticity. These configurations are expected to represent realistic situations as opposed to corotating…

General Relativity and Quantum Cosmology · Physics 2009-10-31 S. Bonazzola , E. Gourgoulhon , J. -A. Marck

A range of speculative space ventures envisage the use of ultra-large structures for the collection and reflection of light. Given the length-scale of such structures they cannot be considered as point masses for the calculation of…

Solar and Stellar Astrophysics · Physics 2026-03-03 Colin R McInnes

In the present paper we investigate self-consistently slowly rotating neutron and strange stars in R-squared gravity. For this purpose we first derive the equations describing the structure of the slowly rotating compact stars in…

General Relativity and Quantum Cosmology · Physics 2015-06-22 Kalin V. Staykov , Daniela D. Doneva , Stoytcho S. Yazadjiev , Kostas D. Kokkotas