Issue |
A&A
Volume 369, Number 2, April II 2001
|
|
---|---|---|
Page(s) | 594 - 604 | |
Section | The Sun | |
DOI | https://doi.org/10.1051/0004-6361:20010079 | |
Published online | 15 April 2001 |
On the oxygen abundance determination in HII regions.
High-metallicity regions
Main Astronomical Observatory of National Academy of Sciences of Ukraine, Goloseevo, 03680 Kiev-127, Ukraine
Received:
26
October
2000
Accepted:
22
December
2000
This is our second paper devoted to the problem of line
intensity -oxygen abundance calibration starting from the idea of McGaugh
([CITE]) that the strong oxygen lines ( and
) contain the necessary information to
determine accurate abundances in HII regions. In the previous study
(Pilyugin 2000) the corresponding relations were obtained for the
low-metallicity HII regions (
, the lower branch of the
O/H -R23 diagram). The high-metallicity HII regions (
, the upper branch of the O/H -R23 diagram) are considered in the
present study.
A relation of the type
) between oxygen abundance and the
value of abundance index R23, introduced by Pagel
et al. ([CITE]), and the excitation parameter P (which is defined here as the
contribution of the radiation in
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 in high-metallicity HII regions
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 (the mean
difference for the 38 HII regions considered is ~0.08 dex)
and is comparable to that of the Te-method.
A relation of the type
) 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 maximum value of differences between electron temperatures determined via
measurement of temperature-sensitive line ratios and those derived with the
suggested relation is around 1000 K for HII regions considered here,
the mean value of differences for 38 HII regions is ~500 K, which is the
same order of magnitude as the uncertainties of electron temperature determinations in
high-metallicity HII regions via measured temperature-sensitive line ratios.
Key words: ISM: HII regions / galaxies: abundances / galaxies: ISM / galaxies: spiral
© ESO, 2001
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