Astronomy and Astrophysics – Astrophysics
Scientific paper
2003-01-22
Astronomy and Astrophysics
Astrophysics
7 pages, 5 figures. To appear in the proceedings of the 8th Tex-Mex Conference on Astrophysics in Rev.Mex.Astr.Astrof. (Serie
Scientific paper
We consider 400 H II galaxies in which the oxygen abundances were obtained by electron temperature based methods. We split the sample in three metallicity bins. In each bin, a narrow sequence is found not only in pure emission line ratio diagrams but also in terms of Hbeta equivalent width, indicating the existence of an evolutionary sequence. Our diagrams show unambiguously the existence of an evolution on a timescale of a few Myr. We compare the observed sequences with photoionization models of appropriate metallicity. In order to understand the evolution of H II galaxies one needs to consider the evolution of the gas as well as that of the stars. The observations require EW(Hbeta) to decrease more rapidly than predicted by the passive evolution of a starburst. A photoionized adiabatic expanding bubble with a covering factor decreasing with time reproduces most diagrams. However, the question of the heating of H II galaxies and the origin of the nebular He II 4686 emission are not settled. We find evidence for self-enrichment in nitrogen on a time scale of several Myr.
Izotov Yuri
Stasinska Grazina
No associations
LandOfFree
The emission line sequence of H II galaxies does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with The emission line sequence of H II galaxies, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and The emission line sequence of H II galaxies will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-198529