SIMBAD references

2012ApJ...753...39P - Astrophys. J., 753, 39 (2012/July-1)

A classification of H II regions based on oxygen and helium lines: the cases of TOL 2146-391 and TOL 0357-3915.


Abstract (from CDS):

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 < t 2 > value for the cases where a direct measurement of t 2 cannot be determined.

Abstract Copyright:

Journal keyword(s): galaxies: abundances - galaxies: individual (TOL2146-391, TOL0357-3915) - galaxies: ISM - H II regions - ISM: abundances

Simbad objects: 35

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