We present preliminary results of stellar structure and nucleosynthesis calculations for some early stars .
The study ( still in progress ) seeks to explore the expected chemical signatures of second generation low- and intermediate-mass stars that may have formed out of a combination of Big Bang and Pop III ( Z=0 ) supernovae material .
Although the study is incomplete at this stage , we find some important features in our models .
The initial chemical composition of these early stars is found to be significantly different to that given by just scaling the solar composition .
The most notable difference is the lack of nitrogen .
This should not affect the structural evolution significantly as nitrogen will be quickly produced through the CNO cycle due to the presence of carbon ( and oxygen ) .
It should however effect the nucleosynthetic yields .
We also find that our very low metallicity 5 M _ { \odot } model , with [ Fe/H ] = -4.01 , does not reach the RGB — it goes directly to the helium burning phase .
It does not experience the first dredge-up either .
This is not a new finding but it will have an effect on the surface chemical evolution of the stars and should alter the nucleosynthetic yields that we are currently calculating .
Our higher metallicity stars , with a globular cluster composition at [ Fe/H ] = -1.4 , do experience all the standard phases of evolution but also have significantly higher surface temperatures and luminosities compared to solar metallicity stars .
Their internal temperatures are also higher which should again effect the final nucleosynthetic yields .