On the oxygen abundance determination in HII regions - The problem of the line intensities - oxygen abundance calibration

The problem of the line intensities - oxygen abundance calibration has been considered. We confirm the idea of McGaugh (1991) that the strong oxygen l ines ([OII]lambda lambda 3727,3729 and [OIII]lambda lambda 4959,5007) conta in the necessary information for determination of accurate abundances in lo w-metallicity land may be also in high-metallicity) H Ir regions. It has be en found that the excitation parameters P-3 or P-2 (which are defined here as contributions of the radiation in [OIII]lambda lambda 4959, 5007 lines a nd in [OII]lambda lambda 3727: 3729 lines to the "total" oxygen radiation r espectively) allow to take into account the variations in R-23 values among HII regions with a given oxygen abundance. Based on this fact a new way of the oxygen abundance determination in HII regions (p - method) has been co nstructed and corresponding relations between [OII]lambda lambda 3727, 3729 , [OIII]lambda lambda 4959, 5007 Line intensities and the oxygen abundance have been derived empirically using the available oxygen abundances determi ned via measurement of temperature-sensitive line ratios (T-e - method). In parallel a new R-23 calibration has been derived on the base of recent d ata and compared to previous calibrations. For oxygen-rich H II regions the present R-23 calibration is close to that of Edmunds & Pagel (1984): their calibration has the same slope but is shifted towards higher oxygen abunda nces by around 0.07 dex as compared to the present calibration.