ﻻ يوجد ملخص باللغة العربية
We select ~20000 metal-rich star-forming galaxies from the SDSS-DR2 to study the R23-P method suggested by Pilyugin et al. for metallicity estimates. The oxygen abundances derived from their revised R23-P method are ~0.19 dex lower than those derived from the previous one, and ~0.60 dex lower than the Bayesian abundances obtained by the MPA/JHU group. These abundance discrepancies strongly correlate with the P parameter and weakly depend on the log(R23) parameter.
During the last three decades, many papers have reported the existence of a luminosity-metallicity or mass-metallicity (M-Z) relation for all kinds of galaxies: The more massive galaxies are also the ones with more metal-rich interstellar medium. We
With this paper we continue the preparation for a forthcoming summary report of our experiment with the Hubble Space Telescope (HST) to determine the Hubble constant using type Ia supernovae as standard candles. Two problems are addressed. (1) We exa
We derive a new relation between the metallicity of Seyfert 2 Active Galactic Nuclei (AGNs) and the intensity of the narrow emission-lines ratio $N2O2$=log([N II]$lambda$6584/[O II]$lambda$3727). The calibration of this relation was performed determi
We analyse the oxygen abundance and specific star formation rates (sSFR) variations with redshift in star-forming SDSS galaxies of different masses. We find that the maximum value of the sSFR, sSFRmax, decreases when the stellar mass, Ms, of a galaxy
We verify whether the O/H abundances of galaxies can be derived from the equivalent width (EW) R23 instead of the extinction-corrected flux R23, and eventually propose a method of improving the reliability of this empirical method, which is often use