An analysis of some properties of stellar models as a function of metallicity Z ( and helium content Y ) is presented , with special attention to those stars with metallicities higher than twice or three times solar .

It is shown that the stellar properties as a function of Z are mainly determined by the effects of the opacities at sub-solar metallicities , and by the effects of the mean molecular weight and stellar mass loss at higher metallicities .
As a result , very metal-rich stars ( Z \mathbin { \raise 1.0 pt \hbox { $ > $ } \kern - 8.0 pt \lower 3.0 pt \hbox { $ \sim$ } } 0.05 ) exhibit properties that deviate from what is expected from the known characteristics at lower metallicities .
In particular , they are more luminous and hotter than those at Z \mathbin { \raise 1.0 pt \hbox { $ < $ } \kern - 8.0 pt \lower 3.0 pt \hbox { $ \sim$ } } 0.05 due to the effect of the mean molecular weight .
They have main sequence lifetimes much shorter ( 60 % shorter at Z = 0.1 than at Z = 0.02 ) than those at solar metallicity due to their lower initial hydrogen content .
Finally , the high mass loss rates at high metallicities affect significantly the population synthesis of massive stars in very metal-rich regions .
An analysis of expected Wolf-Rayet and supernovae populations in such conditions is briefly presented .