Gas-phase metallicity of 27 galaxies at intermediate redshift

Aims: The purpose of this work is to make available new gas-phase oxygen abundance measurements for a serendipitous sample of 27 galaxies with redshifts 0.35 ≤ z ≤ 0.52. Methods: We measured the equivalent widths of the [O II]λ3727, Hβ, and [O III]λλ4959,5007 emission lines observed in the galaxy spectra obtained with the Visible Multi-Object Spectrograph mounted at the Very Large Telescope. For each galaxy, we derived the metallicity-sensitive emission-line ratio R_23, ionization-sensitive emission-line ratio O_32, and gas-phase oxygen abundance 12 + log (O/H). Results: The values of the gas-phase oxygen abundance 12 + log (O/H) that we obtained for all the sample galaxies are consistent with previous findings for galaxies at intermediate redshift.