Evolutionary synthesis models for stellar populations of various ages and chemical compositions are constructed with the approach described in Maraston ( 1998 ) , in which the Fuel Consumption Theorem is used to evaluate the energetics of Post Main Sequence stars .
We present here the synthetic “ stellar ” mass-to-light ratios ( M ^ { * } / L ) in the U,B,V,R,I,J,H,K photometric bands , as functions of age and chemical composition , for single burst populations .
Taking into account the contribution by stellar dead remnants , the computed M ^ { * } / L ratios can be directly compared to those measured in early-type galaxies .
The dependence of M ^ { * } / L ratios on the IMF slope is also explored .
The most interesting result is that the M ^ { * } / L _ { B } ratio of a 15 Gyr stellar population is found to increase by nearly a factor of three , when the chemical composition rises from { [ Fe / H ] } \sim - 0.5 to { [ Fe / H ] } \sim + 0.3 .
This impacts on the interpretation of the tilt of the Fundamental Plane of cluster ellipticals in the B band .