paper

Chemical abundances in 7 metal-poor HII regions and a determination of the primordial helium abundance

arXiv:2105.12260 · doi:10.1093/mnras/stab1543

Abstract

We conducted a long-slit spectrophotometry analysis to obtain the chemical abundances of seven metal-poor HII regions in three galaxies: UM 160, UM 420, and TOL 0513-393. The data have been taken with the Focal Reducer Low Dispersion Spectrograph 1 (FORS1) at the 8.2-m Very Large Telescope. We derived the physical conditions and the chemical abundances of N, O, Ne, S, Ar, and Cl. We also performed a detailed analysis that involves abundance determinations using the formalism. Based on HeI recombination line intensity ratios, together with the Helio14 code, we derived the abundance of He. In addition, for a value , we have estimated that the primordial helium abundance by mass is . This value agrees with values derived from Standard Big Bang Nucleosynthesis and with other recent determinations of .

11 pages, 4 figures. This paper has been accepted in MNRAS

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