Numerical issues on the thermally pulsing AGB stars

Abstract. A version of the stellar evolution code has been developed that uses a non-simultaneous solution of the equations of stellar structure and evolution. In all other respects it is identical to the normal, fully simultaneous version. It is therefore possible to test the effect that solving equations in a non-simultaneous fashion has on the solutions obtained. Two cases are investigated: a 5 M and a 3 M star, both of metallicity Z=0.02. Prior to the asymptotic giant branch, the models are almost identical. However once thermal pulses start, the two methods of solution yield diverging results with the non-simultaneous code predicting longer interpulse periods