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Date and Time of the Query: 2019-06-25 T01:32:05 PDT
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For refcode 2012ApJ...753...39P:
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2012ApJ...753...39P A Classification of H II Regions Based on Oxygen and Helium Lines: The Cases of TOL 2146--391 and TOL 0357--3915 Peimbert, Antonio; Pena-Guerrero, Maria A.; Peimbert, Manuel Abstract. We present long-slit spectrophotometry of two H II galaxies: TOL 2146--391 and TOL 0357--3915. We performed a detailed analysis that involves abundance determinations relaxing the assumption of homogeneous temperature. The temperature inhomogeneity values, t ^2^, were obtained through two methods: (1) comparing abundances from oxygen recombination lines to abundances from collisionally excited lines and (2) by using the line intensity ratios of a set of He I lines together with the HELIO10 program. We find that the HELIO10 program is a good alternative to obtain a t ^2^ value in photoionized regions where recombination lines of heavy elements are not available. We have plotted 27 high- and low-metallicity H II regions in an oxygen degree of ionization versus t ^2^ diagram; we find areas populated by H II regions and areas void of them; the physical characteristics of each area are discussed. In addition, an average t ^2^ value can be determined for the objects in each area. We propose to use this langt ^2^rang value for the cases where a direct measurement of t ^2^ cannot be determined. Based on observations collected at the European Southern Observatory, Chile, proposal number ESO 69.C-0203(A). Key words: galaxies: abundances, galaxies: individual: TOL2146--391 TOL0357--3915, galaxies: ISM, H II regions, ISM: abundances
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