J/A+A/321/29 J/A+A/321/29 Star cluster evolution K Olofsson Astron. Astrophys. 321 29 1997 1997A&A...321...29O Models, evolutionary galaxies: evolution galaxies: starburst galaxies: stellar content A model of spectral evolution of star forming galaxies of various metallicity has been used to study the relation between the optical emission line ratio R_23_=([OII]{lambda}3727+[OIII]{lambda}{lambda}4959,5007)/H{beta} and the nebular oxygen abundance. It is shown that the scatter in an empirical comparison sample could be due to various upper stellar mass limits or different slopes of the stellar initial mass function in these objects.

logQ(H) Number of Lyman continuum photon --- No Running number --- 12+log(O/H) Oxygen abundance --- R23 R23 ([OII]3727+[OIII]4959,5007)/Hbeta) value --- R33 R33 ([OIII]4363+[OIII]4959,5007)) value --- T Temperature of ionizing radiation K fig1.psEmpirical logR_23_ oxygen abundance relation. fig2.psEvolutionary effects on the [OIII]5077/Hbeta emission line ratio. fig3.psEvolution of the emission line ratio [OIII]3727/Hbeta. fig4.psEffect of temporal evolution on the total number of Lyman continuum photons emitted from stellar populations of various metallicity fig5.psR_23_ versus oxygen abundance relation. fig6.psEffects of a non-instantaneous burst of star formation on the R_23_ versus oxygen abundance relation. fig7.psR_23_ versus oxygen abundance under different assumptions about the slope of the IMF and the upper mass limit. fig8.psTheoretical temporal evolution of R_23_ using an instantaneous burst of star formation. fig9.psEffects of a non-instantaneous burst of star formation on the R_23_ versus oxygen abundance relation. fig10.psR_23_ versus oxygen abundance calculated in the interval log(Q(H))=49.0-53.0. fig11.psR_33_ versus oxygen abundance calculated in the interval log(Q(H))=49.0-53.0. fig12.psObjects of Masegosa et al. (1994) as well as Davidson and Kinman (1985) plotted in intervals of T_ion_ in the R_23_ versus oxygen abundance plane. fig13.psCalibrated R_23_ versus oxygen abundance relation. Patricia Bauer CDS 1996Aug12 J_A+A_321_29.xml