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It is known that B\"acklund transformations can be used to generate stationary axisymmetric solutions of Einstein's vacuum field equations with any number of constants. We will use this class of exact solutions to describe the exterior…

General Relativity and Quantum Cosmology · Physics 2011-09-12 C. Teichmüller , M. B. Fröb , F. Maucher

We present a self-consistent, relativistic model of rapidly rotating neutron stars describing their exterior gravitational field. This is achieved by matching the new solution of Einstein's field equations found by Manko et al. (2000) and…

Astrophysics · Physics 2009-11-07 Matthias Stute , Max Camenzind

The macroscopic model for a neutron star (NS) as a perfect liquid drop at the equilibrium is extended to rotating systems by incorporating the linear perturbation expansion over a small frequency $\omega$ near the Schwarzschild…

General Relativity and Quantum Cosmology · Physics 2026-03-09 A. G. Magner , S. P. Maydanyuk , A. Bonasera , H. Zheng , S. N. Fedotkin , A. I. Levon , T. Depastas , U. V. Grygoriev , A. A. Uleiev

When rotation is not taken into account, the measurement of the Gravitational Redshift can provide unique information about the compactness ($M/R$) of the star. Rotation alters the gravitational redshift rendering thereby a unique…

Astrophysics · Physics 2011-06-10 Paul Nunez , Marek Nowakowski

We propose an approximate description of basic parameters (radius, mass and oblateness) of general relativistic compact rotating objects in terms of the parameters of the static configuration and of the angular velocity only. The…

Astrophysics · Physics 2007-05-23 K. S. Cheng , T. Harko

We investigated universal relations for compact stars rotating at the Keplerian (mass-shedding) limit, which is highly relevant for understanding the rapidly rotating objects formed in the aftermath of a neutron star-neutron star merger.…

High Energy Astrophysical Phenomena · Physics 2025-10-15 Pion Sudarshan Yeasin , Stefanos Tsiopelas , Armen Sedrakian , Jia-Jie Li

Exact calculations of innermost stable circular orbit (ISCO) around rotating strange stars are performed within the framework of general relativity. Equations of state (EOS) of strange quark matter based on the MIT Bag Model with massive…

Astrophysics · Physics 2010-11-19 J. L. Zdunik , P. Haensel , D. Gondek-Rosinska , E. Gourgoulhon

Gravitational waves from binary neutron stars in quasiequilibrium circular orbits are computed using an approximate method which we propose in this paper. In the first step of this method, we prepare general relativistic irrotational binary…

General Relativity and Quantum Cosmology · Physics 2009-11-07 Masaru Shibata , Koji Uryu

We investigate the Keplerian (mass-shedding) sequence of rotating neutron stars. Twelve different equations of state are used to describe the nuclear structure. We find four fitting relations which connect the rotating frequency, mass and…

High Energy Astrophysical Phenomena · Physics 2019-02-27 Rashid Riahi , Seyed Zafarollah Kalantari , Jorge Armando Rueda Hernandez

We investigate radial oscillations of pure neutron stars and hybrid stars, employing equations of state of nuclear matter from Brueckner-Hartree-Fock theory, and of quark matter from the Dyson-Schwinger quark model, performing a Gibbs…

Nuclear Theory · Physics 2021-05-12 Ting-Ting Sun , Zi-Yue Zheng , Huan Chen , G. Fiorella Burgio , Hans-Josef Schulze

We investigate the rotational properties of self-bound strange quark stars using two representative quark matter equations of state (EOS): the vector MIT bag model and the density-dependent quark mass (DDQM) model. Through…

High Energy Astrophysical Phenomena · Physics 2026-05-08 Adamu Issifu , Andreas Konstantinou , Franciele M. da Silva , Tobias Frederico

Background: Constraining the nuclear matter equation of state (EoS) from neutron star observations is one of the main subjects in nuclear physics today. In general, neutron stars rotate rapidly and structure of neutron stars can be…

Nuclear Theory · Physics 2025-07-15 Hyukjin Kwon , Kazuyuki Sekizawa

We calculate the range of eigenfrequencies of radial pulsations of stable strange quark stars, using the general relativistic pulsation equation and adopting realistic equation of state for degenerate strange quark matter.

Astrophysics · Physics 2009-10-22 B. Datta , Pradip K. Sahu , J. D. Anand , A. Goyal

Numerical models of rotating neutron stars are constructed for four equations of state using the computer code RNS written by Stergioulas. For five selected values of the star's gravitational mass (in the interval between 1.0 and 1.8 solar…

General Relativity and Quantum Cosmology · Physics 2015-06-25 William G. Laarakkers , Eric Poisson

The back-bending phenomenon for compact stars is studied by means of analytical equations of state, for both constant-pressure phase transitions and the transitions through the mixed-phase region. We restrict ourselves to the case of normal…

Astrophysics · Physics 2007-05-23 J. L. Zdunik , M. Bejger , P. Haensel , E. Gourgoulhon

The frequencies of the highest-frequency kilohertz QPOs recently discovered in some sixteen neutron stars in low-mass X-ray binary systems are most likely orbital frequencies. If so, these QPOs provide tight upper bounds on the masses and…

Astrophysics · Physics 2009-10-30 Frederick K. Lamb , M. Coleman Miller , Dimitrios Psaltis

Rapid uniformly-rotating neutron stars are expected to be formed for instance in the collapse of some massive stars, the accretion of compact object binaries, and double neutron star mergers. The huge amount of the rotational energy has…

High Energy Astrophysical Phenomena · Physics 2026-03-24 Shao-Peng Tang , Yong-Jia Huang , Yi-Zhong Fan

We compute numerical models of uniformly rotating strange stars (SS) in general relativity for the recently proposed QCD-based equation of state (EOS) of strange quark matter (Dey et al. 1998). Static models based on this EOS are…

Astrophysics · Physics 2011-05-12 D. Gondek-Rosinska , T. Bulik , J. L. Zdunik , E. Gourgoulhon , S. Ray , J. Dey , M. Dey

We investigate three-dimensional relativistic trajectories of test particles in the spacetime of a slowly rotating compact star, under the combined influence of gravity and a strong, near-Eddington radiation field. While in the static case…

High Energy Astrophysical Phenomena · Physics 2019-08-07 Maciek Wielgus

Off-equatorial circular orbits with constant latitudes (halo orbits) of electrically charged particles exist near compact objects. In the previous paper, we discussed this kind of motion and demonstrated the existence of minima of the…

High Energy Astrophysical Phenomena · Physics 2010-05-19 Jiri Kovar , Ondrej Kopacek , Vladimir Karas , Zdenek Stuchlik