Keplerian frequency of uniformly rotating neutron stars and quark stars

Understand

We calculate Keplerian (mass shedding) configurations of rigidly rotating neutron stars and quark stars with crusts.

• We check the validity of empirical formula for Keplerian frequency, f_K, proposed by Lattimer & Prakash, f_K(M)=C (M/M_sun)^1/2 (R/10km)^-3/2, where M is the (gravitational) mass of Keplerian configuration, R is the (circumferential) radius of the non-rotating configuration of the same gravitational mass, and C = 1.04 kHz.
• Numerical calculations are performed using precise 2-D codes based on the multi-domain spectral methods.
• We use a representative set of equations of state (EOSs) of neutron stars and quark stars.