The early phases of Milky Way's chemical evolution

Abstract

The earliest phases of the chemical evolution of our Galaxy are analysed in the light of the recent VLT results (concerning abundance patterns in the most metal-poor stars of the Galactic halo) and of stellar nucleosynthesis calculations. It is argued that: 1) the unexpected abundance patterns observed in Pop. II stars are not the imprints of an early generation of supermassive Pop. III stars; 2) among the various suggestions made to exlain the observed abundance patterns, nucleosynthesis in asymmetric supernova explosions appears most promising. In the latter case, an indirect correlation between asymmetry and metallicity is suggested by the data. Finally, the VLT data confirm two old ``puzzles'': the existence of primary N early in Galaxy's evolution (which constrains the mixing of protons with He-burning products in massive stars) and the absence of dispersion in abundance ratios, at least up to the Fe peak, in the early Galaxy (which bears on the timescales of homogeneisation of the interstellar medium, but also on yield variations among massive stars).

arXiv comment10 pages, 4 figures, Review talk in Nuclei in the Cosmos VIII (Eds. L. Buchmann et al.) to appear in NuclPhys A

References in corpus (20)

• The Nucleosynthetic Signature of Population III
• Nucleosynthesis in Chandrasekhar Mass Models for Type Ia Supernovae and Constraints on Progenitor Systems and Burning-Front Propagation
• First stars V - Abundance patterns from C to Zn and supernova yields in the early Galaxy
• The First Stars
• Wilkinson Microwave Anisotropy Probe (WMAP) First Year Observations: TE Polarization
• On the properties of massive Population III stars and metal-free stellar populations
• Stellar evolution with rotation VIII: Models at Z = 10^{-5} and CNO yields for early galactic evolution
• Explosive yields of massive stars from Z=0 to Z=Zsun
• Bipolar Supernova Explosions: Nucleosynthesis & Implication on Abundances in Extremely Metal-Poor Stars
• Cosmic Reionisation by Stellar Sources: Population II Stars
• Explosive Nucleosynthesis in Hypernovae
• The Era of Massive Population III Stars: Cosmological Implications and Self-Termination
• The Stellar Initial Mass Function in Primordial Galaxies
• Nucleosynthesis, Reionization, and the Mass Function of the First Stars
• Stellar Archaeology: a Keck Pilot Program on Extremely Metal-Poor Stars from the Hamburg/ESO Survey. II. Abundance Analysis
• Nucleosynthesis in Type II supernovae and the abundances in metal-poor stars
• Reionisation, chemical enrichment and seed black holes from the first stars: is Population III important?
• Implications of O and Mg abundances in metal-poor halo stars for stellar iron yields
• On the early evolution of the Galactic Halo
• Chemical abundance patterns -- fingerprints of nucleosynthesis in the first stars

Cited by in corpus (4)

• Very low metallicity massive star models: Pre-SN evolution and primary nitrogen production
• Uncovering the Chemical Signature of the First Stars in the Universe
• Very Massive Close Binaries and the Puzzling Temporal Evolution of 14N in the Solar Neighbourhood
• Neutral-Gas-Phase Metal Abundances in ZnII-Selected Quasar Absorption Line Systems near Redshift $z=1.2$