  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 12C, 13C, N, O, and Na and
predict future observations to validate the Pop III nature of HE0107-5240.
