On the minimum period of uniformly rotating neutron stars

We show that the neutron star minimum period of uniform rotation is determi ned, for causal equations of state, by the maximum value of the relativisti c (compactness) parameter 2GM/Rc(2), allowed by causality for static neutro n stars, 0.7081, and by the largest measured mass of a neutron star. The re lation between these three quantities, resulting from the extrapolation of the empirical formulae of Lasota et al. (1996), yields the minimum period o f 0.288 ms, only 2% higher than an absolute lower bound obtained in extensi ve exact numerical calculations of Koranda et al. (1997).