A new tool for the Evolutionary Synthesis of Stellar Populations ( EPS ) is presented , which is based on three independent matrices , giving respectively : 1 ) the fuel consumption during each evolutionary phase as a function of stellar mass ; 2 ) the typical temperatures and gravities during such phases ; 3 ) colours and bolometric corrections as functions of gravity and temperature .
The modular structure of the code allows to easily assess the impact on the synthetic spectral energy distribution of the various assumptions and model ingredients , such as , for example , uncertainties in stellar evolutionary models , mixing length , the temperature distribution of horizontal branch ( HB ) stars , AGB mass loss , and colour-temperature transformations .
The so-called “ AGB-Phase Transition ” in Magellanic Cloud clusters is used to calibrate the contribution of the Thermally Pulsing Asymptotic Giant Branch phase ( TP-AGB ) to the synthetic integrated luminosity .
As an illustrative example , solar metallicity ( Y = 0.27 ,Z = 0.02 ) models , with ages ranging between 30 Myr and 15 Gyr and various choices for the slope of the Initial Mass Function ( IMF ) , are presented .
Synthetic broad band colours and the luminosity contributions of the various evolutionary stages are compared with LMC and Galactic globular cluster data .
In all these cases , a good agreement is found .
Finally , we show the evolution of stellar mass-to-light ratios in the bolometric and U , B , V , R , and K passbands , in which the contribution of stellar remnants is accounted for .