Query : 2009A&A...502..605H

2009A&A...502..605H - Astronomy and Astrophysics, volume 502, 605-610 (2009/8-1)

Keplerian frequency of uniformly rotating neutron stars and strange stars.


Abstract (from CDS):

We calculate Keplerian (mass shedding) configurations of rigidly rotating neutron stars and strange stars with crusts. We check the validity of the empirical formula for Keplerian frequency, fK, proposed by Lattimer & Prakash (2004Sci...304..536L), fK(M)=C(M/M)1/2(R/10km)–3/2, where M is the (gravitational) mass of the Keplerian configuration, R is the (circumferential) radius of the non-rotating configuration of the same gravitational mass, and C=1.04kHz. Numerical calculations are performed using precise 2D codes based on the multi-domain spectral methods. We use a representative set of equations of state (EOSs) of neutron stars and quark stars. We show that the empirical formula for fK(M) holds within a few percent for neutron stars with realistic EOSs, provided 0.5M<M<0.9Mmaxstat, where Mmaxstat is the maximum allowable mass of non-rotating neutron stars for an EOS, and C=CNS=1.08kHz. Similar precision is obtained for strange stars with 0.5M<M<0.9Mmaxstat. For maximal crust masses we obtain CSS=1.15kHz, and the value of CSS is not very sensitive to the crust mass. All our Cs are significantly larger than the analytic value from the relativistic Roche model, CRoche=1.00kHz. For 0.5M<M<0.9Mmaxstat, the equatorial radius of the Keplerian configuration of mass M, RK(M), is, to a very good approximation, proportional to the radius of the non-rotating star of the same mass, RK(M)=a R(M), with aNS≃aSS≃1.44. The value of aSS is very weakly dependent on the mass of the crust of the strange star. Both a values are smaller than the analytic value aRoche=1.5 from the relativistic Roche model.

Abstract Copyright:

Journal keyword(s): dense matter - equation of state - stars: neutron - stars: rotation

Simbad objects: 3

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Number of rows : 3
N Identifier Otype ICRS (J2000)
ICRS (J2000)
Mag U Mag B Mag V Mag R Mag I Sp type #ref
1850 - 2022
1 [KRL2007b] 258 LXB 17 39 53.95 -28 29 46.8           ~ 86 0
2 PSR J1748-2446ad Psr 17 48 04.9 -24 46 04           ~ 99 1
3 PSR B1937+21 Psr 19 39 39.6 +21 37 22           ~ 1013 2

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