# UNIVERSALITY OF THE ACCELERATION DUE TO GRAVITY ON THE SURFACE OF A RAPIDLY ROTATING NEUTRON STAR

@article{Algendy2014UNIVERSALITYOT, title={UNIVERSALITY OF THE ACCELERATION DUE TO GRAVITY ON THE SURFACE OF A RAPIDLY ROTATING NEUTRON STAR}, author={Mohammad Talaat Algendy and Sharon M. Morsink}, journal={The Astrophysical Journal}, year={2014}, volume={791} }

On the surface of a rapidly rotating neutron star, the effective centrifugal force decreases the effective acceleration due to gravity (as measured in the rotating frame) at the equator while increasing the acceleration at the poles due to the centrifugal flattening of the star into an oblate spheroid. We compute the effective gravitational acceleration for relativistic rapidly rotating neutron stars and show that for a star with mass M, equatorial radius Re, and angular velocity Ω, the…

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## References

SHOWING 1-10 OF 44 REFERENCES

### Relativistic Precession around Rotating Neutron Stars: Effects Due to Frame Dragging and Stellar Oblateness

- Physics
- 1999

General relativity predicts that a rotating body produces a frame-dragging (or Lense-Thirring) effect: the orbital plane of a test particle in a nonequatorial orbit precesses about the body's…

### BREAKDOWN OF I–LOVE–Q UNIVERSALITY IN RAPIDLY ROTATING RELATIVISTIC STARS

- Physics
- 2013

It was shown recently that normalized relations between the moment of inertia (I), the quadrupole moment (Q), and the tidal deformability (Love number) exist and for slowly rotating neutron stars…

### The Oblate Schwarzschild Approximation for Light Curves of Rapidly Rotating Neutron Stars

- Physics
- 2007

We present a simple method for including the oblateness of a rapidly rotating neutron star when fitting X-ray light curves. In previous work we showed that the oblateness induced by rotation at…

### Critical radiation fluxes and luminosities of black holes and relativistic stars

- Physics
- 1995

The critial luminosity at which the outward force of radiation balances the inward force of gravity plays an important role in many astrophysical systems. We present expressions for the radiation…

### Rotating neutron stars: an invariant comparison of approximate and numerical space-time models

- Physics
- 2004

We compare three different models of rotating neutron star spacetimes: i) the Hartle-Thorne (1968) slow-rotation approximation, keeping terms up to second order in the stellar angular velocity; ii)…

### Rotating Relativistic Stars

- Physics
- 2013

The masses of neutron stars are limited by an instability to gravitational collapse and an instability driven by gravitational waves limits their spin. Their oscillations are relevant to x-ray…

### Neutron Star Structure and the Equation of State

- Physics
- 2001

The structure of neutron stars is considered from theoretical and observational perspectives. We demonstrate an important aspect of neutron star structure: the neutron star radius is primarily…

### Effectively universal behavior of rotating neutron stars in general relativity makes them even simpler than their Newtonian counterparts.

- PhysicsPhysical review letters
- 2014

A similar, more general, universality is shown to hold true for all rotating neutron stars within general relativity; the first four multipole moments of the neutron star are related in a way independent of the nuclear matter equation of state the authors assume.

### Hydrostatic Expansion and Spin Changes during Type I X-Ray Bursts

- Physics
- 2001

We present calculations of the spin-down of a neutron star atmosphere due to hydrostatic expansion during a type I X-ray burst. We show that Cumming & Bildsten incorrectly calculated the change in…

### Quadrupole Moments of Rotating Neutron Stars

- Physics
- 1999

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…