| Name: | Jeena S K |
| Affiliation: | Indian Institute of Technology Palakkad |
| Conference ID : | ASI2023_40 |
| Title : | Rapidly Rotating Massive Pop III stars: A Solution for High Carbon Enrichment in the Early Galaxy |
| Authors : | Jeena S K,
Projjwal Banerjee :
Department of Physics, Indian Institute of Technology Palakkad, Kerala 678558, India and
Alexander Heger :
School of Physics and Astronomy, Monash University, Victoria, Australia. |
| Mode of Presentation: | Poster |
| Abstract Category : | Stars, ISM and Galaxy |
| Abstract : | Very metal-poor (VMP) stars ([Fe/H]$< -2$) of mass $\lesssim 0.8\, M_\odot$ are thought to be the fossil records of the nucleosynthesis of the earliest generation of massive stars that were present in the early Galaxy. A large fraction of VMP stars are found to be enhanced in C relative to Fe ([C/Fe]$>0.7$) and are referred to as carbon enhanced metal-poor (CEMP) stars. A subclass of CEMP stars that have a low abundance of heavy elements are called CEMP-no stars are thought to be produced from the interstellar medium (ISM) polluted by the supernova ejecta of the very first generation (Pop III) massive stars. Although theoretical models of supernova explosions can explain the relative abundance pattern reasonably well, the very high enrichment of C ([C/H]$\gtrsim -2.5 $) observed in many of the CEMP-no stars is difficult to explain when reasonable values of dilution of the supernova ejecta with the ISM are adopted. We explore rapidly rotating models of Pop III stars that undergo efficient mixing and reach the so-called quasi-chemically homogeneous (QCH) state. We find that rapidly rotating models that reach the QCH state can eject large amounts of C in the wind and the resulting dilution of the wind ejecta in the ISM can naturally explain the high C enrichment observed in CEMP-no stars. We find that rapidly rotating massive Pop III stars are a promising site for explaining the origin of CEMP-no stars. This indicates that a substantial fraction of Pop III stars were rapid rotators. |
