How many metal-poor stars are in the Galactic halo?
Piercarlo Bonifacio (GEPI, Paris, France)
Tuesday 07/05/2024 @ 14:30, Sala Antonio Sollima (IV piano Battiferro)
The chemical enrichment history of a galaxy shapes its Metallicity Distribution Function (MDF). In a hierarchical galaxy formation scenario, a galaxy like the Milky Way is formed by the assembly of smaller galaxies, each of which had its own star formation history and merged into the galaxy at different times. The metal-weak tail of the MDF ([Fe/H] <= -2) is of particular interest because it records the early star formation that likely took place in very small galaxies, it also constrains the initial mass function (IMF) of the first generation of stars (Pop III). In this talk I shall describe what I think is known of the metal-weak tail of the MDF of the Galactic halo and of the accretion event Gaia-Sausage-Enceladus. I will conclude summarising what is known of the low-mass and high-mass extremes of the Pop III IMF.