Volume 441, Number 3, October III 2005
|Page(s)||981 - 997|
|Published online||23 September 2005|
A VLT study of metal-rich extragalactic H II regions
I. Observations and empirical abundances
Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu 96822, USA e-mail: email@example.com
2 Observatoire de Genève, 51 Ch. des Maillettes, 1290 Sauverny, Switzerland e-mail: firstname.lastname@example.org
3 Laboratoire Astrophysique de Toulouse-Tarbes (UMR 5572), Observatoire Midi-Pyrénées, 14 avenue E. Belin, 31400 Toulouse, France
4 Instituto de Astrofísica de Andalucía (CSIC), Apdo. 3004, 18080 Granada, Spain e-mail: email@example.com
5 LUTH, Observatoire de Paris-Meudon, 5 place Jules Jansen, 92195 Meudon, France e-mail: firstname.lastname@example.org
Accepted: 3 June 2005
We have obtained spectroscopic observations from 3600 Åto 9200 Åwith FORS at the Very Large Telescope for approximately 70 H iiregions located in the spiral galaxies NGC 1232, NGC 1365, NGC 2903, NGC 2997 and NGC 5236. These data are part of a project to measure the chemical abundances and characterize the massive stellar content of metal-rich extragalactic H iiregions. In this paper we describe our dataset, and present emission line fluxes for the whole sample. In 32 H iiregions we measure at least one of the following auroral lines: [S ii]4072, [N ii]5755, [S iii]6312 and [O ii]7325. From these we derive electron temperatures, as well as oxygen, nitrogen and sulphur abundances, using classical empirical methods (both so-called “Te-based methods” and “strong line methods”). Under the assumption that the temperature does not introduce severe biases, we find that the most metal-rich nebulae with detected auroral lines are found at 12 + log(O/H) 8.9, i.e. about 60% larger than the adopted solar value. However, classical abundance determinations in metal-rich H iiregions may be severely biased and must be tested with realistic photoionization models. The spectroscopic observations presented in this paper will serve as a homogeneous and high-quality database for such purposes.
Key words: galaxies: abundances / galaxies: ISM / galaxies: stellar content
© ESO, 2005
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