EDP Sciences
Free access
Volume 404, Number 3, June IV 2003
Page(s) 969 - 974
Section Formation, structure and evolution of stars
DOI http://dx.doi.org/10.1051/0004-6361:20030636

A&A 404, 969-974 (2003)
DOI: 10.1051/0004-6361:20030636

Determination of temperature of the ionizing stars of H II regions

O. L. Dors Jr. and M. V. F. Copetti

Laboratório de Análise Numérica e Astrofísica, Departamento de Matemática, Universidade Federal de Santa Maria, 97119-900 Santa Maria, RS, Brazil
(Received 24 January 2003 / Accepted 22 April 2003)

The determination of temperature ( $T_{\rm eff}$) of the ionizing stars of $\ion{H}{ii}$ regions was considered. In this work we used photoionization models for $\ion{H}{ii}$ regions ionized by a single star to show that the index $R=\log\,$([ $\ion{O}{ii}$] $\lambda\lambda$3726+3729/[ $\ion{O}{iii}$] $\lambda$5007) can be used to estimate $T_{\rm eff}$. The relation R vs.  $T_{\rm eff}$ proved to be rather independent of the chemical abundances, but strongly dependent on the ionization parameter of the nebula. In order to check the reliability of using  R for temperature determination, we compared the values of  $T_{\rm eff}$ obtained via the index  R for a sample of $\ion{H}{ii}$ regions with data available in the literature with independent estimations.

Key words: ISM: $\ion{H}{ii}$ regions -- stars: fundamental parameters -- stars: early-type

Offprint request: O. Dors Jr., oli@lana.ccne.ufsm.br

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