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Astron. Astrophys. 362, 325-332 (2000)


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On the oxygen abundance determination in H II regions

The problem of the line intensities - oxygen abundance calibration

L.S. Pilyugin

Main Astronomical Observatory of National Academy of Sciences of Ukraine, Goloseevo, 03680 Kiev-127, Ukraine (pilyugin@mao.kiev.ua)

Received 18 February 2000 / Accepted 21 March 2000

Abstract

The problem of the line intensities - oxygen abundance calibration has been considered. We confirm the idea of McGaugh (1991) that the strong oxygen lines ([FORMULA] and [FORMULA]) 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 [FORMULA] or [FORMULA] (which are defined here as contributions of the radiation in [FORMULA] lines and in [FORMULA] lines to the "total" oxygen radiation respectively) allow to take into account the variations in [FORMULA] 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 [FORMULA], [FORMULA] line intensities and the oxygen abundance have been derived empirically using the available oxygen abundances determined via measurement of temperature-sensitive line ratios ([FORMULA] - method).

In parallel a new [FORMULA] calibration has been derived on the base of recent data and compared to previous calibrations. For oxygen-rich H II regions the present [FORMULA] 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

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