On the oxygen abundance determination in HII regions: High - metallicity regions

This is our second paper devoted to the problem of line intensity - oxygen abundance calibration starting from the idea of McGaugh (1991) that the strong oxygen lines contain the necessary information to determine accurate abundances in HII regions. The high-metallicity HII regions are considered. A relation of the type O/H=f(P,R23) between oxygen abundance and the value of abundance index R23 introduced by Pagel et al. (1979) and the excitation parameter P (which is defined here as the contribution of the radiation in [OIII]4959,5007 lines to the "total" oxygen radiation) has been derived empirically using the available oxygen abundances determined via measurement of a temperature-sensitive line ratio [OIII]4959,5007/[OIII]4363 (Te - method). By comparing oxygen abundances derived with the Te - method and those derived with the suggested relations (P - method), it was found that the precision of oxygen abundance determination with the P - method is around 0.1 dex and is comparable to that of the Te - method. A relation of the type Te=f(P,R23) between electron temperature and the values of abundance index R23 and the excitation parameter P was derived empirically using the available electron temperatures determined via measurement of temperature-sensitive line ratios. The mean difference between electron temperatures derived through the Te=f(P,23 relation and determined via measurement of the temperature-sensitive line ratio is around 500K.