From First Stars to the Spite Plateau: a Possible Reconciliation of Halo Stars Observations with Predictions from Big Bang Nucleosynthesis

Abstract

Since the pioneering observations of Spite & Spite in 1982, the constant lithium abundance of metal-poor ([Fe/H]<-1.3) halo stars near the turnoff has been attributed a cosmological origin. Closer analysis revealed that the observed abundance lies at $\Delta$ Li~0.4 dex below the predictions of Big Bang Nucleosynthesis. The measurements of deuterium abundances on the lines of sight toward quasars and the recent data from the Wilkinson Microwave Anisotropy Probe independently confirmed this gap. We suggest here that part of the discrepancy is explained by the first generation of stars that efficiently depleted lithium. Assuming that the models for lithium evolution in the halo turnoff stars and $\Delta$ Li estimates are correct, we infer that between 1/3 and 1/2 of the baryonic matter of the early halo (~10^9 Mo) was processed through Population III stars. This new paradigm proposes a very economical solution to the lingering difficulty of understanding the properties of the Spite Plateau and its lack of star-to-star scatter down to [Fe/H]=-2.5. It is moreover in agreement both with the absence of lithium detection in the most metal-poor star presently known (HE 1327-2326), and also with new trends of the Plateau suggesting its low metallicity edge may be reached around [Fe/H]=-2.5. We discuss the turbulent mixing associated with enhanced supernovae explosions in the early interstellar medium in this picture. Finally we show that other chemical properties of the extremely metal-poor stars are in agreement with a significant Population III processing in the halo, provided these models include mass-loss and rotationally-induced mixing.

27 pages, 6 figures accepted to the Astrophysical Journal

References in corpus (6)

• Nucleosynthetic signatures of the first stars
• First stars VI - Abundances of C, N, O, Li, and mixing in extremely metal-poor giants. Galactic evolution of the light elements
• A strong case for fast stellar rotation at very low metallicities
• The Frequency of Carbon-Enhanced Metal-Poor Stars in the Galaxy from the HERES sample
• Deuterium astration in the local disc and beyond
• Primordial Stellar Feedback and the Origin of Hyper Metal-Poor Stars

Cited by in corpus (12)

• Carbon Enhanced Metal-Poor Stars. I. Chemical Compositions of 26 Stars
• Primordial Nucleosynthesis: from precision cosmology to fundamental physics
• A probable stellar solution to the cosmological lithium discrepancy
• Atomic Diffusion and Mixing in Old Stars I. VLT/FLAMES-UVES Observations of Stars in NGC 6397
• HE 1327-2326, an unevolved star with [Fe/H]<-5.0. II. New 3D-1D corrected abundances from a VLT/UVES spectrum
• Lithium abundances of halo dwarfs based on excitation temperature. I. LTE
• The Hobby-Eberly Telescope "Chemical Abundances of Stars in the Halo" (CASH) Project. I. The Lithium-, s-, and r-Enhanced Metal-Poor Giant HKII 17435-00532
• The Spatial Distribution of the Galactic First Stars I: High-Resolution N-body Approach
• Near-Infrared Spectroscopy of Carbon-Enhanced Metal-Poor Stars. I. A SOAR/OSIRIS Pilot Study
• Beryllium in Ultra-Lithium-Deficient Halo Stars - The Blue Straggler Connection
• Origin and evolution of the light nuclides
• The halo by halo missing baryon problem