Is Carbon Ubiquitous in the High-Redshift Universe? A Stellar Archaeology perspective

 

 

 

 

The lowest metallicity stars in the Milky Way Halo are the fossil records of the earliest star-forming environments in the universe. The detailed chemical abundance patterns of these stellar relics help us understand primordial nucleosynthesis, the mass function of the first stars, and the pathways that led to the chemical complexity we observe today. However, there is still debate about when (and for how long) the universe transitioned from being metal-free to the first chemical enrichment episodes that triggered low-mass star formation. Furthermore, empirical evidence shows that all the chemically pristine stars observed to date have carbon in their atmospheres at varying levels, suggesting that this element is a key contributor to the chemical evolution of the universe at high redshifts. In this talk, I will review some of the theoretical work on the nature of the first stars and present the discovery of an ultra metal-poor (UMP) star in the halo of the Galaxy with one of the most pristine chemical compositions ever found. SPLUS J2104-0049 is only the 36th UMP star identified in the Milky Way, with the lowest carbon abundance within this group. Comparison with the yields of zero-metallicity supernovae models suggests that this is a bona fide second-generation star, formed from a gas cloud polluted by a single metal-free ~30Mo supernova at early times in the history of the Universe. I will also show current results on observational efforts aiming to find additional UMP stars in the Galaxy.

 

 

 

 

Google Meet: https://meet.google.com/pcw-gmem-jyi

Link da transmissão: https://www.youtube.com/c/AstronomiaIAGUSP/live