On the oxygen abundance determination in H II regions
The problem of the line intensities - oxygen abundance calibration
Received 18 February 2000 / Accepted 21 March 2000
The problem of the line intensities - oxygen abundance calibration has been considered. We confirm the idea of McGaugh (1991) that the strong oxygen lines ( and ) contain the necessary information for determination of accurate abundances in low-metallicity (and may be also in high-metallicity) H II regions. It has been found that the excitation parameters or (which are defined here as contributions of the radiation in lines and in lines to the "total" oxygen radiation respectively) allow to take into account the variations in values among H II regions with a given oxygen abundance. Based on this fact a new way of the oxygen abundance determination in H II regions (p - method) has been constructed and corresponding relations between , line intensities and the oxygen abundance have been derived empirically using the available oxygen abundances determined via measurement of temperature-sensitive line ratios ( - method).
In parallel a new calibration has been derived on the base of recent data and compared to previous calibrations. For oxygen-rich H II regions the present calibration is close to that of Edmunds & Pagel (1984): their calibration has the same slope but is shifted towards higher oxygen abundances by around 0.07 dex as compared to the present calibration.
Key words: ISM: H ii regions galaxies: abundances galaxies: ISM galaxies: irregular galaxies: spiral
© European Southern Observatory (ESO) 2000
Online publication: October 30, 19100