Refining the break-up limit for rapidly rotating neutron stars with fixed baryonic mass.

Neutron stars have a limit to how fast they can rotate before they break apart. Several neutron stars have been observed with rotational frequencies around 500 Hz, but it is unclear how close they are to the breakup frequency. This arises due to the uncertainty in the equation of state for neutron stars. To address this, we have systematically generated families of neutron star equation of states and constructed sequences of them for a star with fixed baryon density. We examine, with current experimental uncertainty of the equation of state, how close the breakup frequency is to the maximum observed neutron star frequency. We also examine the range of possible neutron star radii and moment of inertias possible for stars at the known frequencies of rapidly rotating neutron stars.