The most metal-poor stars offer a unique opportunity to understand early chemical enrichment in galaxies, carrying imprints of the first supernovae (SNe). The Sagittarius (Sgr) dwarf galaxy is ideal for testing chemical evolution and hierarchical accretion models. However, its most metal-poor region remains unexplored.
I will summarize findings from the Pristine Inner Galaxy Survey (PIGS), which hunts the most metal-poor stars in the inner Galaxy and Sgr. I will present results from the largest detailed chemical abundance analysis of very metal-poor stars ([Fe/H]−2.0, as suggested by [Co/Fe] in this range.
In the second part, I will discuss the chemo-dynamical properties of Sgr using a sample of ~350 metal-poor ([Fe/H]+0.7) underestimates the fraction of these stars in dwarf galaxies. We propose adjusting this threshold to [C/Fe]∼+0.35 for Sgr, leading to a similar fraction of CEMP stars between the Milky Way and Sgr.