We elaborate the binary scenario for the origin of HE0107-5240 , the most metal-poor star yet observed ( [ { Fe } / { H } ] = -5.3 ) , using current knowledge of the evolution of extremely metal-poor stars .
From the observed C/N value , we estimate the binary separation and period .
Nucleosynthesis in a helium convective zone into which hydrogen has been injected allows us to discuss the origin of surface O and Na as well as the abundance distribution of s -process elements .
We can explain the observed abundances of ^ { 12 } C , ^ { 13 } C , N , O , and Na and predict future observations to validate the Pop III nature of HE0107-5240 .