The calibration of the O/H abundance indicators for extragalactic H II regions based on O II recombination lines

Based on O II recombination lines we present a new calibration (called O IIRL) of Pagel’s O23 indicator to determine the O/H abundance ratio in extragalactic H II regions and emission line galaxies. The O IIRL calibration produces O/H abundances about a factor of two higher than those derived from the T (4363) method with t 2 = 0.00. The O IIRL calibration has implications for the study of dieren t properties of emission line galaxies such as their metallicity, star formation rate, and initial mass function. The O IIRL calibration also aects the abundance determinations based on other O/H indicators, that include collisionally excited lines, like those known as O3N2, N2, S23, Ar3O3, and S3O3. We argue that the controversy between the T (4363) method and the photoionization models method to derive O/H values is mainly due to temperature variations inside the observed H II regions.