Implications of WMAP Observations on Li Abundance and Stellar Evolution Models

By O. Richard, G. Michaud, Jacques Richer. 2004

217 citations recorded by the source corpus.

The Wilkinson Microwave Anisotropy Probe (WMAP) determination of the baryon-to-photon ratio implies, through big bang nucleosynthesis, a cosmological Li abundance larger, by a factor of 2-3, than the Li abundance plateau observed in the oldest Population II stars. It is, however, inescapable that there be a reduction by a factor of at least 1.6-2.0 of the surface Li abundance during the evolution of Population II field stars with [Fe/H] ≤ -1.5. That the observed Li should be lower than cosmologically produced Li is expected from stellar evolution models. Since at turnoff most of the Li abundance reduction is caused by gravitational settling, the presence of 6Li in some turnoff stars is also understood. Given that the WMAP implications for Li cosmological abundance and the Li Spite plateau can be naturally explained by gravitational settling in the presence of weak turbulence, there appears little need for exotic physics as suggested by some authors. Instead, there is a need for a better understanding of turbulent transport in the radiative zones of stars. This requires simulations from first principles. Rather strict upper limits to turbulent transport are determined for the Sun and Population II stars.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/2fc4a38a9005431f6a787643847201e06d8e4a8c

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In Astronomy and Astrophysics

1. Martin Asplund
2. Timothy C. Beers
3. K. Lind
4. A. Frebel
5. C. Sneden
6. Paul Barklem
7. N. Christlieb
8. V. Hill

In Instrumentation

1. Martin Asplund
2. Timothy C. Beers
3. K. Lind
4. V. Hill
5. Paul Barklem
6. T. Sivarani
7. B. Barbuy
8. R. Collet

Citations in the corpus

• Precision big bang nucleosynthesis with improved Helium-4 predictions (2018, background): “Li evolution could affect its abundance by introducing the effects of convective overshooting, atomic diffusion and mixing (Richard et al., 2005).”
• Atomic Diffusion and Mixing in Old Stars. I. Very Large Telescope FLAMES-UVES Observations of Stars in NGC 6397 (2007, methodology): “Magnesium As lines of silicon are not detected in our spectra, we use magnesium as an element for which the stellar-structure models of Richard et al. (2005) predict trends very similar to silicon (∆ log ε (Mg) = 0.2, see §3.5).”
• Signatures of intrinsic Li depletion and Li-Na anti-correlation in the metal-poor globular cluster NGC 6397 , (2009, methodology): “By comparing this observed abundance diff rence of Li (as well as Fe, Ca, Mg, and Ti) to predictions from the stellar-structure models by Richard et al. (2005) and references therein, Korn et al. empirically constrain the efficiency of slow macroscopic motions counteracting atomic diffusion below…”
• First stars VII - Lithium in extremely metal poor dwarfs (2006, background): “In this regard, it is of significance that recent investigations of the effects of diffusion (with the inclusion of turbulence: Richard et al. 2002a,b; Michaud et al. 2004; Richard et al. 2005) have been able to reproduce the Li-Teff dependence found by Ryan et al. (1999).”