SIMBAD references

2007ApJ...666..636P - Astrophys. J., 666, 636-646 (2007/September-2)

Revised primordial helium abundance based on new atomic data.


Abstract (from CDS):

We have derived a primordial helium abundance of Yp=0.2477±0.0029, based on new atomic physics computations of the recombination coefficients of He I and of the collisional excitation of the H I Balmer lines together with observations and photoionization models of metal-poor extragalactic H II regions. The new atomic data increase our previous determination of Yp by 0.0086, a very significant amount. By combining our Ypresult with the predictions made by the standard big bang nucleosynthesis model, we find a baryon-to-photon ratio, η, in excellent agreement both with the η-value derived by the primordial deuterium abundance value observed in damped Lyα systems and with the one obtained from the WMAP observations.

Abstract Copyright:

Journal keyword(s): Cosmology: Early Universe - Galaxies: Abundances - Galaxies: Individual: Alphanumeric: SBS 0335-052 - Galaxies: Individual: Alphanumeric: I Zw 18 - galaxies: individual (Haro 29) - Galaxies: ISM - ISM: H II Regions - ISM: Abundances

Simbad objects: 10

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