at the stellar surface are the various isotopes of carbon and nitrogen. The surface abundances of both elements are listed in Table \[tab1\]. It is evident that the He-flash induced H-flash, if operating in real Pop. III stars, produces very significant changes in the chemical composition of the star, preventing its identification as a  metal-free star.

As a result of the dredge-up of metal-rich matter, the low-temperature opacity is increased drastically. This produces an abrupt jump in the effective temperature visible in the HR-diagram (Fig. \[fig2\]; indicated by the dotted part of the track).

The ceasing fusion of He after the H-flash yields a new-born shell H-burning object, climbing up its own RGB. However, this time the H-burning shell is moving through a helium-rich region and the energy production rate is quite large in comparison with the previous evolution. About 50 million years after the first He-flash, when the He core mass is equal to $0.452\,M_\odot$, a second He-flash develops at $M_r=0.027\,M_\odot$. The smaller He core mass and the – compared to the first flash – lower $M(\epsilon^{\rm He}_{\rm max})$ can both be explained by a substantial decrease of the central electron degeneracy during the previous He ignition. This argument 