Colóquios do NAT

06/05 - The earliest chemical enrichment encoded in ancient stars

Dra.  Asa Skuladottir (University of Groningen)

The Milky Way is an environment rich with satellite galaxies, stellar streams and accreted systems. Encoded in these structures is the formation and evolution of the Galaxy throughout cosmic time. Fortunately, these nearby relics can be studied in extraordinary detail – star by star – revealing the properties of the first stars, the build-up of chemical elements in the Universe, the nature of dark matter, and hierarchical galaxy formation. Here, I will talk about some recent insights from these Milky Way satellite galaxies, focusing on the earliest chemical enrichment. This includes the discovery of AS0039, one of the most metal-poor stars found in any external galaxy. This star represents some of the first observational evidence for zero-metallicity hypernova (10 times the explosion energy of a normal supernova) and provides a unique opportunity to investigate the diverse nature of the first stars. Furthermore, I will contrast observations in the dwarf galaxies with that of the Milky Way, to try to better understand what kind of systems built up the metal-poor Galactic halo. Finally, I will introduce my upcoming large spectroscopic survey: 4DWARFS - a 4MOST survey of dwarf galaxies and their stellar streams. 4DWARFS is a 5 year survey which will increase the number of stars with detailed abundance information in dwarf galaxies and stellar streams by several orders of magnitude.