Evolutionary synthesis of simple stellar populations

We construct evolutionary synthesis models for simple stellar populations using the evolutionary tracks from the Padova group (1993, 1994), theoretical colour calibrations from [Lejeune et al. (1997, 1998)] and fit functions for stellar atmospheric indices from [Worthey et al. (1994)]. A Monte-Carlo technique allows us to obtain a smooth time evolution of both broad band colours in UBVRIK and a series of stellar absorption features for Single Burst Stellar Populations ( SSPs ). We present colours and indices for SSPs with ages from yrs to yrs and metallicities , -1.7, -0.7, -0.4, 0.0 and 0.4. Model colours and indices at an age of about a Hubble time are in good agreement with observed colours and indices of the Galactic and M 31 GCs.