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ABSTRACT We conducted a long-slit spectrophotometry analysis to obtain the chemical abundances of seven metal-poor H ii 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 t2 formalism. Based on He i recombination line intensity ratios, together with the HELIO 14 code, we derived the abundance of He. In addition, for a value Y/ ZO =3. 3 0. 7, we have estimated that the primordial helium abundance by mass is YP = 0. 2448 ± 0. 0033. This value agrees with values derived from Standard Big Bang Nucleosynthesis and with other recent determinations of YP.
Valerdi et al. (Tue,) studied this question.