Related papers: Primordial helium abundance determination using su…
The precision measurement of the primordial helium abundance $Y_p$ is a powerful probe of the early Universe. The most common way to determine $Y_p$ is analyses of observations of metal-poor \HII regions found in blue compact dwarf…
We introduce a new statistical method to estimate the primordial helium abundance, Y_p from observed abundances in a sample of galaxies which have experienced stellar helium enrichment. Rather than using linear regression on metal abundance…
I present a brief review on the determination of the primordial helium abundance by unit mass, Yp. I discuss the importance of the primordial helium abundance in: (a) cosmology, (b) testing the standard big bang nucleosynthesis, (c)…
Observations of metal-poor extragalactic H II regions allow the determination of the primordial helium abundance, Y_p. The He I emissivities are the foundation of the model of the H II region's emission. Porter, Ferland, Storey, & Detisch…
To understand the Universe a highly accurate ($\sim$1%) primordial helium abundance (Yp) determination plays an important role; it is extremely important to constrain: Big Bang Nucleosynthesis models, elementary particle physics, and the…
Almost every helium atom in the Universe was created just a few minutes after the Big Bang through a process commonly referred to as Big Bang Nucleosynthesis. The amount of helium that was made during Big Bang Nucleosynthesis is determined…
We present a review on the determination of the primordial helium abundance, Yp, based on the study of hydrogen and helium recombination lines in extragalactic H II regions. We also discuss the observational determinations of the increase…
We include new data in an updated analysis of helium in low metallicity extragalactic HII regions with the goal of deriving the primordial abundance of He4 (Y_P). We show that the new observations of Izotov et al (ITL) are consistent with…
Currently, the primordial helium abundance is best estimated through spectroscopic observations of H II regions in metal-poor galaxies. However these determinations are limited by several systematic uncertainties which ultimately limit our…
A reanalysis is made for the helium abundance determination for the Izotov-Thuan (2004) spectroscopic sample of extragalactic H II regions. We find that the effect of underlying stellar absorption of the He I lines, which is more important…
Observational measures of the primordial helium mass fraction, $Y_{\rm P}$, are of interest for cosmology and fundamental particle physics. Current measures obtained from H II regions agree with the Standard Model prediction to…
Based on observations of HII regions and the new computations of the recombination coefficients of the He I lines by Porter et al. (2013) we obtain a primordial helium abundance by mass of $Y_P = 0.2446\pm0.0029$. We consider thirteen…
We present a new constraint on the primordial helium abundance, $Y_\mathrm{P}$, based on Subaru observations. A major source of uncertainty in previous $Y_\mathrm{P}$ determinations is the lack of extremely metal-poor galaxies (EMPGs;…
Currently there are two significantly different observational determinations of the primordial helium abundance, and, if only statistical errors in He4 abundance determinations are considered, the discrepancies between the observational…
We present a review on the determination of the primordial helium abundance Yp, based on the study of hydrogen and helium recombination lines in extragalactic HII regions. We also discuss the observational determinations of the increase of…
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…
We determine the primordial helium mass fraction Yp using 93 spectra of 86 low-metallicity extragalactic HII regions. This sample constitutes the largest and most homogeneous high-quality data sets in existence for the determination of Yp.…
Recent advances on the quest to determine the primordial or pregalactic helium abundance, Yp, are reviewed. There are seven problems affecting the He/H abundance determinations of H II regions that are briefly discussed: the underlying…
The primordial abundance of 4He, Y_P, is one of the hottest themes in present-day astronomy, mostly due to its cosmological relevance. The disagreement between different determinations has been currently reduced to the 1-2 percent level,…
The primordial $^4$He abundance (Y$_p$) is one of the key characteristics of Primordial Nucleosynthesis processes that occurred in the first minutes after the Big Bang. Its value depends on the baryon/photon ratio $\eta\equiv…