Abundance determinations in H II regions
Model fitting versus –method
Main Astronomical Observatory of National Academy of Sciences of Ukraine, 27 Zabolotnogo str., 03680 Kiev, Ukraine
Corresponding author: firstname.lastname@example.org
Accepted: 18 October 2002
The discrepancy between the oxygen abundances in high-metallicity H ii regions determined through the Te–method (and/or through the corresponding “strong lines – oxygen abundance” calibration) and that determined through the model fitting (and/or through the corresponding “strong lines – oxygen abundance” calibration) is discussed. It is suggested to use the interstellar oxygen abundance in the solar vicinity, derived with very high precision from the high-resolution observations of the weak interstellar OIλ1356 absorption lines towards the stars, as a “Rosetta stone” to verify the validity of the oxygen abundances derived in H ii regions with the Te–method at high abundances. The agreement between the value of the oxygen abundance at the solar galactocentric distance traced by the abundances derived in H ii regions through the Te–method and that derived from the interstellar absorption lines towards the stars is strong evidence in favor of that i) the two-zone model for Te seems to be a realistic interpretation of the temperature structure within H ii regions, and ii) the classic Te–method provides accurate oxygen abundances in H ii regions. It has been concluded that the “strong lines – oxygen abundance” calibrations must be based on the H ii regions with the oxygen abundances derived with the Te–method but not on the existing grids of the models for H ii regions.
Key words: ISM: H ii regions / galaxies: abundances / galaxies: ISM
© ESO, 2003