We carry out 3-D numerical simulations of the dynamical instability in rapidly rotating stars initially modeled as polytropes with n = 1.5 , 1.0 , and 0.5 .
The calculations are done with a SPH code using Newtonian gravity , and the gravitational radiation is calculated in the quadrupole limit .
All models develop the global m = 2 bar mode , with mass and angular momentum being shed from the ends of the bar in two trailing spiral arms .
The models then undergo successive episodes of core recontraction and spiral arm ejection , with the number of these episodes increasing as n decreases : this results in longer-lived gravitational wave signals for stiffer models .
This instability may operate in a stellar core that has expended its nuclear fuel and is prevented from further collapse due to centrifugal forces .
The actual values of the gravitational radiation amplitudes and frequencies depend sensitively on the radius of the star R _ { eq } at which the instability develops .