On the oxygen abundance determination in HII regions.

Free access article

Issue		A&A Volume 369, Number 2, April II 2001


Page(s)		594 - 604
Section		Diffuse matter in space
DOI		http://dx.doi.org/10.1051/0004-6361:20010079

A&A 369, 594-604 (2001)
DOI: 10.1051/0004-6361:20010079

High-metallicity regions

L. S. Pilyugin

Main Astronomical Observatory of National Academy of Sciences of Ukraine, Goloseevo, 03680 Kiev-127, Ukraine

(Received 26 October 2000 / Accepted 22 December 2000)

Abstract
This is our second paper devoted to the problem of line intensity -oxygen abundance calibration starting from the idea of McGaugh (1991) that the strong oxygen lines ( $[{\rm OII}] \lambda \lambda 3727, 3729$ and $[{\rm OIII}] \lambda \lambda 4959, 5007$ ) 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 ( $12+{\rm log O/H} \leq 7.95$ , the lower branch of the O/H -R₂₃ diagram). The high-metallicity HII regions ( $12+{\rm log O/H} \geq 8.2$ , the upper branch of the O/H -R₂₃ diagram) are considered in the present study. A relation of the type ${\rm O/H}=f(P, R_{23}$ ) between oxygen abundance and the value of abundance index R₂₃, introduced by Pagel et al. (1979), and the excitation parameter P (which is defined here as the contribution of the radiation in $[{\rm OIII}] \lambda \lambda 4959, 5007$ 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 ( $T_{\rm e}$ -method). By comparing oxygen abundances in high-metallicity HII regions derived with the $T_{\rm e}$ -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 $T_{\rm e}$ -method. A relation of the type $T_{\rm e}=f(P, R_{23}$ ) 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

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.