Speaker
Description
The most iron-poor stars are thought to be among the oldest objects observable in the sky.
Understanding them provides us a deeper knowledge on formation and evolution of the pristine universe.
In fact, they are supposed to be formed from a gas enriched just by the explosion of the first generation of massive stars.
Their chemical inventory has the signature of the nucleosynthesis both during the life of the first-generation massive stars,
and in the supernovae explosion. It is then very sensitive to the masses of the first stellar generation.
Another key point is to detect binarity among these stars to understand how they formed.
The very few stars known with a really poor iron-content ([Fe/H]<-4.5) show diversity in their chemical content and peculiarities.
Some of them show variability in radial velocity, compatible with belonging to a multiple system.
With the aid of new observations, we investigated the binarity of some of these ultra Fe-poor stars, in particular the prototype ultra iron-poor star HE0107-5240 and other ultra Fe-poor stars.
We re-visited their chemical contents with particular attention to C isotopic ratio, sensitive to the nucleosynthesis of a possible more evolved candidate in the binary system during the asymptotic giant branch.
