Fitting Rotational Frequency of Polytropes as a Function of their Oblateness

Abstract Giving a simple functional relationship between the rotational frequency and the centrifugal deformation for compressible stellar models is useful both in observational and theoretical astrophysics. Here I present simple Padé approximants for the rotational frequency of polytropic stars (index N = 1, 1.5, 3) as a function of the oblateness, which are valid at the order of  [ 10 − 2 ] percent for the speed of rotation up to the mass-shedding limit.