scholarly journals Measurements of 4He in metal-poor extragalactic H ii regions: the primordial Helium abundance and the ΔY/ΔO ratio

2009 ◽  
Vol 5 (S268) ◽  
pp. 91-100 ◽  
Author(s):  
Manuel Peimbert ◽  
A. Peimbert ◽  
L. Carigi ◽  
V. Luridiana
Keyword(s):  
Chemical Evolution ◽  
H Ii Regions ◽  
Helium Abundance ◽  
Galactic Chemical Evolution ◽  
Primordial Helium

AbstractWe 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 of helium to the increase of oxygen by mass ΔY/ΔO, and compare them with predictions based on models of galactic chemical evolution.

scholarly journals The Magellanic Clouds and the Primordial Helium Abundance

2000 ◽  
Vol 198 ◽  
pp. 194-203 ◽  
Author(s):  
Manuel Peimbert ◽  
Antonio Peimbert
Keyword(s):  
Neutral Hydrogen ◽  
Magellanic Clouds ◽  
Heavy Elements ◽  
H Ii Regions ◽  
Helium Abundance ◽  
Temperature Variations ◽  
Systematic Effects ◽  
H Ii Region ◽  
Primordial Helium

A new determination of the pregalactic helium abundance based on the Magellanic Clouds H II regions is discussed. This determination amounts to Yp = 0.2345 ± 0.0030 and is compared with those derived from giant extragalactic H II regions in systems with extremely low heavy elements content. It is suggested that the higher primordial value derived by other authors from giant H II region complexes could be due to two systematic effects: the presence of neutral hydrogen inside the helium Strömgren sphere and the presence of temperature variations inside the observed volume.

scholarly journals The Helium-to-Metals Enrichment Ratio in Planetary Nebulae

1993 ◽  
Vol 155 ◽  
pp. 583-583
Author(s):  
C.M.L. Chiappini ◽  
W.J. Maciel
Keyword(s):  
Chemical Evolution ◽  
Planetary Nebulae ◽  
Hii Regions ◽  
Big Bang ◽  
Enrichment Ratio ◽  
Helium Abundance ◽  
Galactic Chemical Evolution ◽  
Big Bang Theory ◽  
The Big Bang

The helium-to-metals enrichment ratio (dY/dZ) and the pregalactic helium abundance (Yp) are important parameters for the understanding of the galactic chemical evolution, and also as a cosmological test to the Big Bang theory. In this work, we present a new determination of these parameters based on a sample of galactic HII regions, HII galaxies, and planetary nebulae.

scholarly journals A new determination of the primordial helium abundance using the analyses of H ii region spectra from SDSS

2021 ◽  
Vol 502 (2) ◽  
pp. 3045-3056
Author(s):  
O A Kurichin ◽  
P A Kislitsyn ◽  
V V Klimenko ◽  
S A Balashev ◽  
A V Ivanchik
Keyword(s):  
Sloan Digital Sky Survey ◽  
H Ii Regions ◽  
Helium Abundance ◽  
Physical Conditions ◽  
Sky Survey ◽  
H Ii Region ◽  
Standard Cosmological Model ◽  
Primordial Helium ◽  
Good Agreement

ABSTRACT The precision measurement of the primordial helium abundance Yp is a powerful probe of the early Universe. The most common way to determine Yp is the analyses of observations of metal-poor H ii regions found in blue compact dwarf galaxies. We present the spectroscopic sample of 100 H ii regions collected from the Sloan Digital Sky Survey. The final analysed sample consists of our sample and HeBCD data base from Izotov et al. (2007). We use a self-consistent procedure to determine physical conditions, current helium abundances, and metallicities of the H ii regions. From a regression to zero metallicity, we have obtained Yp = 0.2462 ± 0.0022, which is one of the most stringent constraints obtained with such methods up to date and is in a good agreement with the Planck result $Y_{\rm p}^{\it {\mathrm{ Planck}}} = 0.2471 \pm 0.0003$. Using the determined value of Yp and the primordial deuterium abundance taken from Particle Data Group (Zyla et al. 2020) we put a constraint on the effective number of neutrino species Neff = 2.95 ± 0.16, which is consistent with the Planck one Neff = 2.99 ± 0.17. Further increase of statistics potentially allows us to achieve Planck accuracy, which in turn will become a powerful tool for studying the self-consistency of the standard cosmological model and/or physics beyond.

scholarly journals On the total O/H abundance ratio in Galactic and extragalactic H ii regions

2009 ◽  
Vol 5 (S268) ◽  
pp. 185-186
Author(s):  
Antonio Peimbert ◽  
Manuel Peimbert
Keyword(s):  
Gas Phase ◽  
Chemical Evolution ◽  
Abundance Ratio ◽  
Phase Fraction ◽  
H Ii Regions ◽  
Helium Abundance ◽  
Phase Component ◽  
Evolution Of Galaxies ◽  
Primordial Helium

AbstractTo determine the primordial helium abundance and to study the chemical evolution of galaxies it is necessary to derive the total O/H ratio in H ii regions. To determine the total O/H ratio in H ii regions it is necessary to add to the gas-phase component the dust-phase component of O atoms. Based on the Fe/O ratio and other considerations we estimate the dust-phase fraction as a function of O/H.

scholarly journals Determination of the Primordial Helium Abundance Based on NGC 346, an H ii Region of the Small Magellanic Cloud

2019 ◽  
Vol 876 (2) ◽  
pp. 98 ◽  
Author(s):  
Mabel Valerdi ◽  
Antonio Peimbert ◽  
Manuel Peimbert ◽  
Andrés Sixtos
Keyword(s):  
Magellanic Cloud ◽  
Helium Abundance ◽  
Small Magellanic Cloud ◽  
H Ii Region ◽  
Primordial Helium

scholarly journals Planetary Nebulae and the Pregalactic Helium Abundance

1989 ◽  
Vol 131 ◽  
pp. 213-213 ◽  
Author(s):  
Walter J. Maciel
Keyword(s):  
Chemical Composition ◽  
Recent Work ◽  
Planetary Nebulae ◽  
H Ii Regions ◽  
Helium Abundance

Recent work has emphasized the determination of the pregalactic helium abundance by mass Yp and the slope ΔY/ΔZ based on the chemical composition of both galactic and extragalactic H II regions (Pagel, 1987; Pagel et al., 1986).

The Effect of Collisional Enhancement of Balmer Lines on the Determination of the Primordial Helium Abundance

2003 ◽  
Vol 592 (2) ◽  
pp. 846-865 ◽  
Author(s):  
V. Luridiana ◽  
A. Peimbert ◽  
M. Peimbert ◽  
M. Cervino
Keyword(s):  
Helium Abundance ◽  
Balmer Lines ◽  
Primordial Helium

scholarly journals The Composition of H II Regions in the Magellanic Clouds

1984 ◽  
Vol 108 ◽  
pp. 353-361 ◽  
Author(s):  
Reginald J. Dufour
Keyword(s):  
Chemical Composition ◽  
Chemical Evolution ◽  
Magellanic Clouds ◽  
The State ◽  
H Ii Regions ◽  
Galactic Chemical Evolution

The state of our knowledge concerning the chemical composition of H II regions in the Magellanic Clouds is reviewed. New abundances derived from all modern published spectroscopy are presented. Some of the implications of the results regarding the nucleosynthesis of the elements and galactic chemical evolution are noted.

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